In 1692 an artist known only as “A. Boogert” sat down to write a book in Dutch about mixing watercolors. Not only would he begin the book with a bit about the use of color in painting, but would go on to explain how to create certain hues and change the tone by adding one, two, or three parts of water.

Spanning nearly 800 completely handwritten (and painted) pages, Traité des couleurs servant à la peinture à l’eau, was probably the most comprehensive guide to paint and color of its time.

Via Colossal.
PDF of the original book can be seen on e-corpus.