white is to be kept as much as possible out of shadow, and black, for the same reason, out of colour, employing opaque tints in each case, instead of black or white, whenever it is necessary to cover, and glazing them with transparent colours. Such practice would also be more favourable to durability of the tones of pictures than the shades and tints produced with black and white. The hues and shadows of Nature are in no ordinary case either black or white, which are always poor, frigid, and fearful in colouring, except as local colours.

For this doctrine we have also the high authority of Rubens, who, in the following extract from his Lessons, says, "Begin by painting in your shadows lightly, taking particular care that no white is suffered to glide into them; it is the poison of a picture, except in the lights: if once your shadows are corrupted by the introduction of this baneful colour, your tones will be no longer warm and transparent, but heavy and leady. It is not the same in the lights; they may be loaded with [opaque] colour as much as you may think proper, provided the tones are kept pure: you are sure to succeed in placing each tint in its place, and afterwards by a light blending with the brush or pencil, melting them into each other without tormenting them, and on this preparation may be given those decided touches which are always the distinguishing marks of the great master;" and, although in

G

modes of practice differing from that of Rubens, the contrary of this precept has been followed, yet, as it applies only to the upper painting, the principle itself is universal.

It is to be noted also, that the colour of shadow is always complementary to that of its light, modified by the local colours upon which it falls; and this accords equally with correct observation and the foregoing principles, although these are at variance with the ordinary practice of artists.

Of the mechanical, dynamical, and optical relations of light and shade, so far as regards painting and colours, we need only briefly remark, that the motion or action of light is either direct, reflected, or inflected; that the direct lights of the sun and moon are always in straight lines nearly parallel to each other;—that artificial lights diverge from themselves as centres in radii, and all light partakes of the colour of the medium through which it passes; — that of reflected light, the angles of reflection are always equal to the angles of incidence, and partake of the colours of the reflected surfaces; and, respecting refracted lights, that in passing through transparent media, or by opaque objects, light, whether direct or reflected, is always inflected with a developement also of much or little colour; and that the shadows of light in each case is always the chromatic equivalent of such light. Opticians regard the motion of the sun's light as propagated in parallel rays,

and attribute the like parallelism to other lights, abating always the diameter of the agents, and this may be very allowable as a mathematical fiction, but cannot be maintained as a fact; for light is an infinite agent, diffusing itself expansively from every point and particle, till utterly expanded or expended in darkness, the patient of light, according to its various affinities: and to this we owe the penumbræ of shadows, and all the effects of transient colours from prisms, lenses, and transparent solids and of colours meteorological and spectral.

In passing an opaque object, light is always bent or inflected toward, or into, its shadow, and the shadow bends into the light; consequently, there is a penumbra surrounding every shade, forming a softening medium between it and the light, and aiding reflection in enlightening every shade; every light has hence its shade, and every shadow its light. It is in the management of these properties of light that the skill of the artist is no less requisite and conspicuous than in the management of colours, with which they are intimately connected.

To conclude, we know not whether the preceding attempt to explain the causes and effects of vision, light, and colours, physically or chemically, may prove satisfactory to other minds; but of this we feel assured, that the first elements of things are powers and not particles; that the modern corpuscular and undulatory doctrines, with all the

mathematical and mechanical explanations hitherto employed, are entirely incompetent to the solution of these phenomena; and that all the hypotheses built upon them, like those which they superseded,⁕ must ultimately fail at the foundation, not even answering the inquiry of the poet :—

"Why does one climate and one soil endue
The blushing poppy with an orange hue,

Yet leave the lily pale, and tinge the violet blue?"

Prior.

⁕ Of the best of these was that often quoted of Empedocles, the Pythagorean, from which school has emanated some of the most refined and important of antient and modern systems;— but with this hypothesis, which accounted for vision by the emission of light from the eye, the powerful mind of Socrates declared itself not thoroughly satisfied; indeed, it is the extreme opposed to common sense and modern doctrine (as was also the solar system of Pythagoras), and truth lies not in extremes but in a medium which connects them.—See Sydenham's "Plato: Meno," p. 75.

CHAPTER V.

ON THE DURABILITY AND FUGACITY OF COLOURS.

"Parthenius thinks in Reynolds' steps he treads,
And ev'ry day a different palette spreads;
Now bright in vegetable bloom he glows,
His white—the lily, and his red—the rose ;
But soon aghast, amid his transient hues,

The ghost of his departed picture views:

Now burning minerals, fossils, bricks, and bones,

He seeks more durable in dusky tones,

And triumphs in such permanence of dye,

That all seems fix'd, which time would wish to fly."

Shee.

In the preceding discussion colours are distinguished into inherent and transient, the latter of which, as their name implies, are essentially fugacious; our present argument is, therefore, limited to the permanence and mutability of the inherent colours of pigments, as those which are principally important to the artist.

All durability of colour is relative, because all material substances are changeable and in perpetual action and reaction; there is, therefore, no pigment so permanent as that nothing will change its colour, nor any colour so fugitive as not to last under some favouring circumstances; while time