Theory of Colours — trans. Charles Lock Eastlake (1840)

As a pigment it cannot be produced by intermixture or union, but only by arresting the hue in substances chemically acted on, at the high culminating point. Hence the painter is justified in assuming that there are _three_ primitive colours from which he combines all the others. The natural philosopher, on the other hand, assumes only _two_ elementary colours, from which he, in like manner, developes and combines the rest.

COMPLETENESS THE RESULT OF VARIETY IN COLOUR.

706.

The various appearances of colour arrested in their different degrees, and seen in juxtaposition, produce a whole. This totality is harmony to the eye.

707.

The chromatic circle has been gradually presented to us; the various relations of its progression are apparent to us. Two pure original principles in contrast, are the foundation of the whole; an augmentation manifests itself by means of which both approach a third state; hence there exists on both sides a lowest and highest, a simplest and most qualified state. Again, two combinations present themselves; first that of the simple primitive contrasts, then that of the deepened contrasts.

HARMONY OF THE COMPLETE STATE.

708.

The whole ingredients of the chromatic scale, seen in juxtaposition, produce an harmonious impression on the eye. The difference between the physical contrast and harmonious opposition in all its extent should not be overlooked. The first resides in the pure restricted original dualism, considered in its antagonizing elements; the other results from the fully developed effects of the complete state.

709.

Every single opposition in order to be harmonious must comprehend the whole. The physiological experiments are sufficiently convincing on this point. A development of all the possible contrasts of the chromatic scale will be shortly given.[3]

FACILITY WITH WHICH COLOUR MAY BE MADE TO TEND EITHER TO THE PLUS OR
MINUS SIDE.

710.

We have already had occasion to take notice of the mutability of colour in considering its so-called augmentation and progressive variations round the whole circle; but the hues even pass and repass from one side to the other, rapidly and of necessity.

711.

Physiological colours are different in appearance as they happen to fall on a dark or on a light ground. In physical colours the combination of the objective and subjective experiments is very remarkable. The epoptical colours, it appears, are contrasted according as the light shines through or upon them. To what extent the chemical colours may be changed by fire and alkalis, has been sufficiently shown in its proper place.

EVANESCENCE OF COLOUR.

712.

All that has been adverted to as subsequent to the rapid excitation and definition of colour, immixture, augmentation, combination, separation, not forgetting the law of compensatory harmony, all takes place with the greatest rapidity and facility; but with equal quickness colour again altogether disappears.

713.

The physiological appearances are in no wise to be arrested; the physical last only as long as the external condition lasts; even the chemical colours have great mutability, they may be made to pass and repass from one side to the other by means of opposite re-agents, and may even be annihilated altogether.

PERMANENCE OF COLOUR.

714.

The chemical colours afford evidence of very great duration. Colours fixed in glass by fusion, and by nature in gems, defy all time and re-action.

715.

The art of dyeing again fixes colour very powerfully. The hues of pigments which might otherwise be easily rendered mutable by re-agents, may be communicated to substances in the greatest permanency by means of mordants.

[1] Wirkung, Beraubung; the last would be more literally rendered _privation_. The author has already frequently made use of the terms _active_ and _passive_ as equivalent to _plus_ and _minus_.--T.

[2] Wherever this word occurs incidentally it is translated _pure red_, the English word _purple_ being generally employed to denote a colour similar to violet.--T.

[3] No diagram or table of this kind was ever given by the author.--T.

PART V.

RELATION TO OTHER PURSUITS--RELATION TO PHILOSOPHY.

716.

The investigator of nature cannot be required to be a philosopher, but it is expected that he should so far have attained the habit of philosophizing, as to distinguish himself essentially from the world, in order to associate himself with it again in a higher sense. He should form to himself a method in accordance with observation, but he should take heed not to reduce observation to mere notion, to substitute words for this notion, and to use and deal with these words as if they were things. He should be acquainted with the labours of philosophers, in order to follow up the phenomena which have been the subject of his observation, into the philosophic region.

717.