It is very unlikely that you should meet with one of the original etchings; if you should, it will be a drawing-master in itself alone, for it is not only equivalent to a pen-and-ink drawing by Turner, but to a very careful one: only observe, the Source of Arveron, Raglan, and Dumblane were not etched by Turner; and the etchings of those three are not good for separate study, though it is deeply interesting to see how Turner, apparently provoked at the failure of the beginnings in the Arveron and Raglan, took the plates up himself, and either conquered or brought into use the bad etching by his marvellous engraving. The Dumblane was, however, well etched by Mr. Lupton, and beautifully engraved by him. The finest Turner etching is of an aqueduct with a stork standing in a mountain stream, not in the published series; and next to it, are the unpublished etchings of the Via Mala and Crowhurst.

Turner seems to have been so fond of these plates that he kept retouching and finishing them, and never made up his mind to let them go. The Via Mala is certainly, in the state in which Turner left it, the finest of the whole series: its etching is, as I said, the best after that of the aqueduct. Figure 20., above, is part of another fine unpublished etching, "Windsor, from Salt Hill." Of the published etchings, the finest are the Ben Arthur, aesacus, Cephalus, and Stone Pines, with the Girl washing at a Cistern; the three latter are the more generally instructive. Hindhead Hill, Isis, Jason, and Morpeth, are also very desirable.

[223] You will find more notice of this point in the account of Harding's tree-drawing, a little farther on.

[224] The impressions vary so much in colour that no brown can be specified.

[225] You had better get such a photograph, even if you have a Liber print as well.

[226] See the closing letter in this volume.

[227] Bogue, Fleet Street. If you are not acquainted with Harding's works (an unlikely supposition, considering their popularity), and cannot meet with the one in question, the diagrams given here will enable you to understand all that is needful for our purposes.

[228] I draw this figure (a young shoot of oak) in outline only, it being impossible to express the refinements of shade in distant foliage in a woodcut.

[229] His lithographic sketches, those, for instance, in the Park and the Forest, and his various lessons on foliage, possess greater merit than the more ambitious engravings in his "Principles and Practice of Art." There are many useful remarks, however, dispersed through this latter work.

[230] On this law you will do well, if you can get access to it, to look at the fourth chapter of the fourth volume of "Modern Painters."

[231] The student may hardly at first believe that the perspective of buildings is of little consequence: but he will find it so ultimately.

See the remarks on this point in the Preface.

[232] It is a useful piece of study to dissolve some Prussian blue in water, so as to make the liquid definitely blue: fill a large white basin with the solution, and put anything you like to float on it, or lie in it; walnut sh.e.l.ls, bits of wood, leaves of flowers, &c. Then study the effects of the reflections, and of the stems of the flowers or submerged portions of the floating objects, as they appear through the blue liquid; noting especially how, as you lower your head and look along the surface, you see the reflections clearly; and how, as you raise your head, you lose the reflections, and see the submerged stems clearly.

[233] Respecting Architectural Drawing, see the notice of the works of Prout in the Appendix.

LETTER III.

ON COLOUR AND COMPOSITION.

MY DEAR READER:--

If you have been obedient, and have hitherto done all that I have told you, I trust it has not been without much subdued remonstrance, and some serious vexation. For I should be sorry if, when you were led by the course of your study to observe closely such things as are beautiful in colour, you had not longed to paint them, and felt considerable difficulty in complying with your restriction to the use of black, or blue, or grey. You _ought_ to love colour, and to think nothing quite beautiful or perfect without it; and if you really do love it, for its own sake, and are not merely desirous to colour because you think painting a finer thing than drawing, there is some chance you may colour well. Nevertheless, you need not hope ever to produce anything more than pleasant helps to memory, or useful and suggestive sketches in colour, unless you mean to be wholly an artist. You may, in the time which other vocations leave at your disposal, produce finished, beautiful, and masterly drawings in light and shade. But to colour well, requires your life. It cannot be done cheaper. The difficulty of doing right is increased--not twofold nor threefold, but a thousandfold, and more--by the addition of colour to your work. For the chances are more than a thousand to one against your being right both in form and colour with a given touch: it is difficult enough to be right in form, if you attend to that only; but when you have to attend, at the same moment, to a much more subtle thing than the form, the difficulty is strangely increased--and multiplied almost to infinity by this great fact, that, while form is absolute, so that you can say at the moment you draw any line that it is either right or wrong, colour is wholly _relative_.

Every hue throughout your work is altered by every touch that you add in other places; so that what was warm a minute ago, becomes cold when you have put a hotter colour in another place, and what was in harmony when you left it, becomes discordant as you set other colours beside it; so that every touch must be laid, not with a view to its effect at the time, but with a view to its effect in futurity, the result upon it of all that is afterwards to be done being previously considered. You may easily understand that, this being so, nothing but the devotion of life, and great genius besides, can make a colourist.

But though you cannot produce finished coloured drawings of any value, you may give yourself much pleasure, and be of great use to other people, by occasionally sketching with a view to colour only; and preserving distinct statements of certain colour facts--as that the harvest-moon at rising was of such and such a red, and surrounded by clouds of such and such a rosy grey; that the mountains at evening were in truth so deep in purple; and the waves by the boat's side were indeed of that incredible green. This only, observe, if you have an eye for colour; but you may presume that you have this, if you enjoy colour.

And, though of course you should always give as much form to your subject as your attention to its colour will admit of, remember that the whole value of what you are about depends, in a coloured sketch, on the colour _merely_. If the colour is wrong, everything is wrong: just as, if you are singing, and sing false notes, it does not matter how true the words are. If you sing at all, you must sing sweetly; and if you colour at all, you must colour rightly. Give up _all_ the form, rather than the slightest part of the colour: just as, if you felt yourself in danger of a false note, you would give up the word, and sing a meaningless sound, if you felt that so you could save the note. Never mind though your houses are all tumbling down--though your clouds are mere blots, and your trees mere k.n.o.bs, and your sun and moon like crooked sixpences--so only that trees, clouds, houses, and sun or moon, are of the right colours. Of course, the discipline you have gone through will enable you to hint something of form, even in the fastest sweep of the brush; but do not let the thought of form hamper you in the least, when you begin to make coloured memoranda. If you want the form of the subject, draw it in black and white. If you want its colour, take its colour, and be sure you _have_ it, and not a spurious, treacherous, half-measured piece of mutual concession, with the colours all wrong, and the forms still anything but right. It is best to get into the habit of considering the coloured work merely as supplementary to your other studies; making your careful drawings of the subject first, and then a coloured memorandum separately, as shapeless as you like, but faithful in hue, and entirely minding its own business. This principle, however, bears chiefly on large and distant subjects; in foregrounds and near studies, the colour cannot be had without a good deal of definition of form. For if you do not map the mosses on the stones accurately, you will not have the right quant.i.ty of colour in each bit of moss pattern, and then none of the colours will look right; but it always simplifies the work much if you are clear as to your point of aim, and satisfied, when necessary, to fail of all but that.

Now, of course, if I were to enter into detail respecting colouring, which is the beginning and end of a painter's craft, I should need to make this a work in three volumes instead of three letters, and to ill.u.s.trate it in the costliest way. I only hope at present to set you pleasantly and profitably to work, leaving you, within the tethering of certain leading-strings, to gather what advantages you can from the works of art of which every year brings a greater number within your reach;--and from the instruction which, every year, our rising artists will be more ready to give kindly, and better able to give wisely.

And, first, of materials. Use hard cake colours, not moist colours: grind a sufficient quant.i.ty of each on your palette every morning, keeping a separate plate, large and deep, for colours to be used in broad washes, and wash both plate and palette every evening, so as to be able always to get good and pure colour when you need it; and force yourself into cleanly and orderly habits about your colours. The two best colourists of modern times, Turner and Rossetti,[234] afford us, I am sorry to say, no confirmation of this precept by their practice.

Turner was, and Rossetti is, as slovenly in all their procedures as men can well be; but the result of this was, with Turner, that the colours have altered in all his pictures, and in many of his drawings; and the result of it with Rossetti is, that, though his colours are safe, he has sometimes to throw aside work that was half done, and begin over again.

William Hunt, of the Old Water-colour, is very neat in his practice; so, I believe, is Mulready; so is John Lewis; and so are the leading Pre-Raphaelites, Rossetti only excepted. And there can be no doubt about the goodness of the advice, if it were only for this reason, that the more particular you are about your colours the more you will get into a deliberate and methodical habit in using them, and all true _speed_ in colouring comes of this deliberation.

Use Chinese white, well ground, to mix with your colours in order to pale them, instead of a quant.i.ty of water. You will thus be able to shape your ma.s.ses more quietly, and play the colours about with more ease; they will not damp your paper so much, and you will be able to go on continually, and lay forms of pa.s.sing cloud and other fugitive or delicately shaped lights, otherwise unattainable except by time.

This mixing of white with the pigments, so as to render them opaque, const.i.tutes _body_-colour drawing as opposed to _transparent_-colour drawing and you will, perhaps, have it often said to you that this body-colour is "illegitimate." It is just as legitimate as oil-painting, being, so far as handling is concerned, the same process, only without its uncleanliness, its unwholesomeness, or its inconvenience; for oil will not dry quickly, nor carry safely, nor give the same effects of atmosphere without tenfold labour. And if you hear it said that the body-colour looks chalky or opaque, and, as is very likely, think so yourself, be yet a.s.sured of this, that though certain effects of glow and transparencies of gloom are not to be reached without transparent colour, those glows and glooms are _not_ the n.o.blest aim of art. After many years' study of the various results of fresco and oil painting in Italy, and of body-colour and transparent colour in England, I am now entirely convinced that the greatest things that are to be done in art must be done in dead colour. The habit of depending on varnish or on lucid tints transparency, makes the painter comparatively lose sight of the n.o.bler translucence which is obtained by breaking various colours amidst each other: and even when, as by Correggio, exquisite play of hue is joined with exquisite transparency, the delight in the depth almost always leads the painter into mean and false chiaroscuro; it leads him to like dark backgrounds instead of luminous ones,[235] and to enjoy, in general, quality of colour more than grandeur of composition, and confined light rather than open sunshine: so that the really greatest thoughts of the greatest men have always, so far as I remember, been reached in dead colour, and the n.o.blest oil pictures of Tintoret and Veronese are those which are likest frescos.

Besides all this, the fact is, that though sometimes a little chalky and coa.r.s.e-looking, body-colour is, in a sketch, infinitely liker nature than transparent colour: the bloom and mist of distance are accurately and instantly represented by the film of opaque blue (_quite_ accurately, I think, by _nothing_ else); and for ground, rocks, and buildings, the earthy and solid surface is, of course, always truer than the most finished and carefully wrought work in transparent tints can ever be.

Against one thing, however, I must steadily caution you. All kinds of colour are equally illegitimate, if you think they will allow you to alter at your pleasure, or blunder at your ease. There is _no_ vehicle or method of colour which admits of alteration or repentance; you must be right at once, or never; and you might as well hope to catch a rifle bullet in your hand, and put it straight, when it was going wrong, as to recover a tint once spoiled. The secret of all good colour in oil, water, or anything else, lies primarily in that sentence spoken to me by Mulready: "Know what you have to do." The process may be a long one, perhaps: you may have to ground with one colour; to touch it with fragments of a second; to crumble a third into the interstices; a fourth into the interstices of the third; to glaze the whole with a fifth; and to reinforce in points with a sixth: but whether you have one, or ten, or twenty processes to go through, you must go _straight_ through them, knowingly and foreseeingly all the way; and if you get the thing once wrong, there is no hope for you but in washing or sc.r.a.ping boldly down to the white ground, and beginning again.

The drawing in body-colour will tend to teach you all this, more than any other method, and above all it will prevent you from falling into the pestilent habit of sponging to get texture; a trick which has nearly ruined our modern water-colour school of art. There are sometimes places in which a skilful artist will roughen his paper a little to get certain conditions of dusty colour with more ease than he could otherwise; and sometimes a skilfully rased piece of paper will, in the midst of transparent tints, answer nearly the purpose of chalky body-colour in representing the surfaces of rocks or buildings. But artifices of this kind are always treacherous in a tyro's hands, tempting him to trust in them; and you had better always work on white or grey paper as smooth as silk;[236] and never disturb the surface of your colour or paper, except finally to scratch out the very highest lights if you are using transparent colours.

I have said above that body-colour drawing will teach you the use of colour better than working with merely transparent tints; but this is not because the process is an easier one, but because it is a more _complete_ one, and also because it involves _some_ working with transparent tints in the best way. You are not to think that because you use body-colour you may make any kind of mess that you like, and yet get out of it. But you are to avail yourself of the characters of your material, which enable you most nearly to imitate the processes of Nature. Thus, suppose you have a red rocky cliff to sketch, with blue clouds floating over it. You paint your cliff first firmly, then take your blue, mixing it to such a tint (and here is a great part of the skill needed), that when it is laid over the red, in the thickness required for the effect of the mist, the warm rock-colour showing through the blue cloud-colour, may bring it to exactly the hue you want; (your upper tint, therefore, must be mixed colder than you want it;) then you lay it on, varying it as you strike it, getting the forms of the mist at once, and, if it be rightly done, with exquisite quality of colour, from the warm tint's showing through and between the particles of the other. When it is dry, you may add a little colour to retouch the edges where they want shape, or heighten the lights where they want roundness, or put another tone over the whole; but you can take none away. If you touch or disturb the surface, or by any untoward accident mix the under and upper colours together, all is lost irrecoverably.

Begin your drawing from the ground again if you like, or throw it into the fire if you like. But do not waste time in trying to mend it.[237]

This discussion of the relative merits of transparent and opaque colour has, however, led us a little beyond the point where we should have begun; we must go back to our palette, if you please. Get a cake of each of the hard colours named in the note below[238] and try experiments on their simple combinations, by mixing each colour with every other. If you like to do it in an orderly way, you may prepare a squared piece of pasteboard, and put the pure colours in columns at the top and side; the mixed tints being given at the intersections, thus (the letters standing for colours):

b c d e f &c.

a ab ac ad ae af b -- bc bd be bf c -- -- cd ce cf d -- -- -- de df e -- -- -- -- ef &c.

This will give you some general notion of the characters of mixed tints of two colours only, and it is better in practice to confine yourself as much as possible to these, and to get more complicated colours, either by putting a third _over_ the first blended tint, or by putting the third into its interstices. Nothing but watchful practice will teach you the effects that colours have on each other when thus put over, or beside, each other.

[Ill.u.s.tration: FIG. 29.]

When you have got a little used to the princ.i.p.al combinations, place yourself at a window which the sun does not shine in at, commanding some simple piece of landscape; outline this landscape roughly; then take a piece of white cardboard, cut out a hole in it about the size of a large pea; and supposing _R_ is the room, _a d_ the window, and you are sitting at _a_, Fig. 29., hold this cardboard a little outside of the window, upright, and in the direction _b d_, parallel a little turned to the side of the window, or so as to catch more light, as at _a d_, never turned as at _c d_, or the paper will be dark. Then you will see the landscape, bit by bit, through the circular hole. Match the colours of each important bit as nearly as you can, mixing your tints with white, beside the aperture. When matched, put a touch of the same tint at the top of your paper, writing under it: "dark tree colour," "hill colour,"

"field colour," as the case may be. Then wash the tint away from beside the opening, and the cardboard will be ready to match another piece of the landscape.[239] When you have got the colours of the princ.i.p.al ma.s.ses thus indicated, lay on a piece of each in your sketch in its right place, and then proceed to complete the sketch in harmony with them, by your eye.

In the course of your early experiments, you will be much struck by two things: the first, the inimitable brilliancy of light in sky and in sunlighted things: and the second, that among the tints which you can imitate, those which you thought the darkest will continually turn out to be in reality the lightest. Darkness of objects is estimated by us, under ordinary circ.u.mstances, much more by _knowledge_ than by sight; thus, a cedar or Scotch fir, at 200 yards off, will be thought of darker green than an elm or oak near us; because we know by experience that the peculiar colour they exhibit, at that distance, is the _sign_ of darkness of foliage. But when we try them through the cardboard, the near oak will be found, indeed, rather dark green, and the distant cedar, perhaps, pale gray-purple. The quant.i.ty of purple and grey in Nature is, by the way, another somewhat surprising subject of discovery.

Well, having ascertained thus your princ.i.p.al tints, you may proceed to fill up your sketch; in doing which observe these following particulars:

1. Many portions of your subject appeared through the aperture in the paper brighter than the paper, as sky, sunlighted gra.s.s, &c. Leave these portions, for the present, white; and proceed with the parts of which you can match the tints.

2. As you tried your subject with the cardboard, you must have observed how many changes of hue took place over small s.p.a.ces. In filling up your work, try to educate your eye to perceive these differences of hue without the help of the cardboard, and lay them deliberately, like a mosaic-worker, as separate colours, preparing each carefully on your palatte, and laying it as if it were a patch of coloured cloth, cut out, to be fitted neatly by its edge to the next patch; so that the _fault_ of your work may be, not a slurred or misty look, but a patched bed-cover look, as if it had all been cut out with scissors. For instance, in drawing the trunk of a birch tree, there will be probably white high lights, then a pale rosy grey round them on the light side, then a (probably greenish) deeper grey on the dark side, varied by reflected colours, and over all, rich black strips of bark and brown spots of moss. Lay first the rosy grey, leaving white for the high lights _and for the spots of moss_, and not touching the dark side. Then lay the grey for the dark side, fitting it well up to the rosy grey of the light, leaving also in this darker grey the white paper in the places for the black and brown moss; then prepare the moss colours separately for each spot, and lay each in the white place left for it.

Not one grain of white, except that purposely left for the high lights, must be visible when the work is done, even through a magnifying-gla.s.s, so cunningly must you fit the edges to each other. Finally, take your background colours, and put them on each side of the tree-trunk, fitting them carefully to its edge.

Fine work you would make of this, wouldn't you, if you had not learned to draw first, and could not now draw a good outline for the stem, much less terminate a colour ma.s.s in the outline you wanted?

Your work will look very odd for some time, when you first begin to paint in this way, and before you can modify it, as I shall tell you presently how; but never mind; it is of the greatest possible importance that you should practice this separate laying on of the hues, for all good colouring finally depends on it. It is, indeed, often necessary, and sometimes desirable, to lay one colour and form boldly over another: thus, in laying leaves on blue sky, it is impossible always in large pictures, or when pressed for time, to fill in the blue through the interstices of the leaves; and the great Venetians constantly lay their blue ground first, and then, having let it dry, strike the golden brown over it in the form of the leaf, leaving the under blue to shine through the gold, and subdue it to the olive green they want. But in the most precious and perfect work each leaf is inlaid, and the blue worked round it: and, whether you use one or other mode of getting your result, it is equally necessary to be absolute and decisive in your laying the colour.

Either your ground must be laid firmly first, and then your upper colour struck upon it in perfect form, for ever, thenceforward, unalterable; or else the two colours must be individually put in their places, and led up to each other till they meet at their appointed border, equally, thenceforward, unchangeable. Either process, you see, involves _absolute_ decision. If you once begin to slur, or change, or sketch, or try this way and that with your colour, it is all over with it and with you. You will continually see bad copyists trying to imitate the Venetians, by daubing their colours about, and retouching, and finishing, and softening: when every touch and every added hue only lead them farther into chaos. There is a dog between two children in a Veronese in the Louvre, which gives the copyist much employment. He has a dark ground behind him, which Veronese has painted first, and then when it was dry, or nearly so, struck the locks of the dog's white hair over it with some half-dozen curling sweeps of his brush, right at once, and forever. Had one line or hair of them gone wrong, it would have been wrong forever; no retouching could have mended it. The poor copyists daub in first some background, and then some dog's hair; then retouch the background, then the hair, work for hours at it, expecting it always to come right to-morrow--"when it is finished." They _may_ work for centuries at it, and they will never do it. If they can do it with Veronese's allowance of work, half a dozen sweeps of the hand over the dark background, well; if not, they may ask the dog himself whether it will ever come right, and get true answer from him--on Launce's conditions: "If he say 'ay,' it will; if he say 'no,' it will; if he shake his tail and say nothing, it will."

Whenever you lay on a ma.s.s of colour, be sure that however large it may be, or however small, it shall be gradated. No colour exists in Nature under ordinary circ.u.mstances without gradation. If you do not see this, it is the fault of your inexperience; you _will_ see it in due time, if you practise enough. But in general you may see it at once. In the birch trunk, for instance, the rosy grey _must_ be gradated by the roundness of the stem till it meets the shaded side; similarly the shaded side is gradated by reflected, light. Accordingly, whether by adding water, or white paint, or by unequal force of touch (this you will do at pleasure, according to the texture you wish to produce), you must, in every tint you lay on, make it a little paler at one part than another, and get an even gradation between the two depths. This is very like laying down a formal law or recipe for you; but you will find it is merely the a.s.sertion of a natural fact. It is not indeed physically impossible to meet with an ungradated piece of colour, but it is so supremely improbable, that you had better get into the habit of asking yourself invariably, when you are going to copy a tint,--not "_Is_ that gradated?" but "_Which way_ is it gradated?" and at least in ninety-nine out of a hundred instances, you will be able to answer decisively after a careful glance, though the gradation may have been so subtle that you did not see it at first. And it does not matter how small the touch of colour may be, though not larger than the smallest pin's head, if one part of it is not darker than the rest, it is a bad touch; for it is not merely because the natural fact is so, that your colour should be gradated; the preciousness and pleasantness of the colour itself depends more on this than on any other of its qualities, for gradation is to colours just what curvature is to lines, both being felt to be beautiful by the pure instinct of every human mind, and both, considered as types, expressing the law of gradual change and progress in the human soul itself. What the difference is in mere beauty between a gradated and ungradated colour, may be seen easily by laying an even tint of rose-colour on paper, and putting a rose leaf beside it. The victorious beauty of the rose as compared with other flowers, depends wholly on the delicacy and quant.i.ty of its colour gradations, all other flowers being either less rich in gradation, not having so many folds of leaf; or less tender, being patched and veined instead of flushed.

4. But observe, it is not enough in general that colour should be gradated by being made merely paler or darker at one place than another.

Generally colour _changes_ as it _diminishes_, and is not merely _darker_ at one spot, but also _purer_ at one spot than anywhere else.

It does not in the least follow that the darkest spot should be the purest; still less so that the lightest should be the purest. Very often the two gradations more or less cross each other, one pa.s.sing in one direction from paleness to darkness, another in another direction from purity to dullness, but there will almost always be both of them, however reconciled; and you must never be satisfied with a piece of colour until you have got both: that is to say, every piece of blue that you lay on must be _quite_ blue only at some given spot, nor that a large spot; and must be gradated from that into less pure blue--greyish blue, or greenish blue, or purplish blue, over all the rest of the s.p.a.ce it occupies. And this you must do in one of three ways: either, while the colour is wet, mix it with the colour which is to subdue it, adding gradually a little more and a little more; or else, when the colour is quite dry, strike a gradated touch of another colour over it, leaving only a point of the first tint visible: or else, lay the subduing tints on in small touches, as in the exercise of tinting the chess-board. Of each of these methods I have something to tell you separately: but that is distinct from the subject of gradation, which I must not quit without once more pressing upon you the preeminent necessity of introducing it everywhere. I have profound dislike of anything like _habit_ of hand, and yet, in this one instance, I feel almost tempted to encourage you to get into a habit of never touching paper with colour, without securing a gradation. You will not in Turner's largest oil pictures, perhaps six or seven feet long by four or five high, find one spot of colour as large as a grain of wheat ungradated: and you will find in practice, that brilliancy of hue, and vigour of light, and even the aspect of transparency in shade, are essentially dependent on this character alone; hardness, coldness, and opacity resulting far more from _equality_ of colour than from nature of colour. Give me some mud off a city crossing, some ochre out of a gravel pit, a little whitening, and some coal-dust, and I will paint you a luminous picture, if you give me time to gradate my mud, and subdue my dust: but though you had the red of the ruby, the blue of the gentian, snow for the light, and amber for the gold, you cannot paint a luminous picture, if you keep the ma.s.ses of those colours unbroken in purity, and unvarying in depth.

5. Next note the three processes by which gradation and other characters are to be obtained:

A. Mixing while the colour is wet.

You may be confused by my first telling you to lay on the hues in separate patches, and then telling you to mix hues together as you lay them on: but the separate ma.s.ses are to be laid, when colours distinctly oppose each other at a given limit; the hues to be mixed, when they palpitate one through the other, or fade one into the other. It is better to err a little on the distinct side. Thus I told you to paint the dark and light sides of the birch trunk separately, though in reality, the two tints change, as the trunk turns away from the light, gradually one into the other: and, after being laid separately on, will need some farther touching to harmonize them: but they do so in a very narrow s.p.a.ce, marked distinctly all the way up the trunk; and it is easier and safer, therefore, to keep them separate at first. Whereas it often happens that the whole beauty of two colours will depend on the one being continued well through the other, and playing in the midst of it: blue and green often do so in water: blue and grey, or purple and scarlet, in sky; in hundreds of such instances the most beautiful and truthful results may be obtained by laying one colour into the other while wet; judging wisely how far it will spread, or blending it with the brush in somewhat thicker consistence of wet body-colour; only observe, never mix in this way two _mixtures_; let the colour you lay into the other be always a simple, not a compound tint.