The first is produced by the preponderance of the active side, the second by that of the passive side, and the third by completeness, by the exhibition of the whole chromatic scale in due balance.
The powerful impression is attained by yellow, yellow-red, and red, which last colour is to be arrested on the plus side. But little violet and blue, still less green, are admissible. The soft effect is produced by blue, violet, and red, which in this case is arrested on the minus side; a moderate addition of yellow and yellow-red, but much green may be admitted.
If it is proposed to produce both these effects in their full significancy, the complemental colours may be excluded to a minimum, and only so much of them may be suffered to appear as is indispensable to convey an impression of completeness.