HARMONY.
11. Harmony results from an agreeable contrast.
12. Colours which perfectly harmonise improve one another to the utmost.
13. In order to perfect harmony, the three colours are necessary, either in their purity or in combination.
14. Red and green combine to yield a harmony. Red is a primary colour, and green, which is a secondary colour, consists of blue and yellow—the other two primary colours. Blue and orange also produce a harmony, and yellow and purple, for in each ease the three primary colours are present.
15. It has been found that the primary colours in perfect purity produce exact harmonies in the proportions of eight parts of blue, 5 of red, and 3 of yellow; that the secondary colours harmonise in the proportions of 13 of purple, 11 of green, and 8 of orange; and that the tertiary colours harmonise in the proportions of olive 24, russet 21, and citrine 19.
16. There are, however, subtleties of harmony which it is difficult to understand.
17. The rarest harmonies frequently lie close on the verge of discord.
18. Harmony of colour is, in many respects, analogous to harmony of musical sounds.