Male and female represent the two sides of the great radical dualism. But, in fact, they are perpetually passing into one another. Fluid hardens to solid, solid rushes to fluid. There is no wholly masculine man, no purely feminine woman.
History jeers at the attempts of physiologists to bind great original laws by the forms which flow from them. They make a rule; they say from observation what can and cannot be. In vain! Nature provides exceptions to every rule. She sends women to battle, and sets Hercules spinning; she enables women to bear immense burdens, cold, and frost; she enables the man, who feels maternal love, to nourish his infant like a mother.

Woman in the Nineteenth Century (1845)