Lewis Day took a complicated subject and dove right in. Once I got a handle on the geometric interplay that occurs in designing patterns, I was much better able to understand the depth of the subject which he describes. He is intelligent, well-spoken, open, thorough, and includes a wealth of design instruction here. Although the book was first published in 1903, and Day writes in a somewhat romantic form typical of the time, his knowledge and practicality on the topic places him solidly in the present. I did have trouble with his occasional racial comments though; he was clearly a product of his time and the statements were startling when I came across them. The material is dense and this is no quick read, but it's a treasure trove of information.