El origen del hombre
The book critiques Charles Darwin four years after he published "The Descent of Man, and Selection in Relation to Sex" in 1871, and Herbert Spencer, whom the author thought were the most influential men of her day. Darwin had written a letter to her in 1869, thanking her for a copy of her book, "Studies in General Science". She also answers Dr. E. H. Clarke and his book "Sex and Education" which she deplored. Blackwell's book was republished by Hyperion Press in 1976, 1985 and 1992. Parts of the book were first published in "Woman's Journal" and "Popular Science Monthly".