Darwin believed that the difference between males and females were partly due to "sexual selection".
[1] Darwin concludes in his book, The Descent of Man, saying that men attain "a higher eminence, in whatever he takes up, than can women—whether requiring deep thought, reason, or imagination, or merely the use of the senses and hands.
The letters show private thoughts and actions which are different to the gender ideology held by common middle-class Victorians.
The letters show that in private Darwin relied on various women for some of his work including his daughter Henrietta who helped in editing The Descent of Man.
Dixie also wrote a book which created the fantasy of a world where men and women were equals.