The issue of sexual love permeates Blake’s work. I suspect that Blake produced even more explicitly sexual work, but since most of his work wasn’t really published, when his wife died in 1831, the bulk of his manuscripts and paintings were subject to the whims of their unsophisticated owners. But on the basis of his existing work, it is reasonable to say that sexual and imaginative energy was the motor that Blake saw producing intellectual advancement. This male-female principle of change was more fully explored by Blake than by anyone previously, since he made it concrete and personal, rather than abstract.
--Dr. Ray Peat
from Can Art Instruct Science? William Blake as Biological Visionary