The meaning of a saying by Balzac

"Voilà," says Bèebè Francillon, fanning herself languidly. "That is the way with men. Flatter them, and they kiss your hand. Loose but a moment the silken leash that holds them captive through their vanity and self-opinionativeness, and the son-of-a-gun gets on his ear at once. The devil go with him, I say."

"Ah, mon Princesse," sighs the Count Pumpernickel, stooping and whispering with eloquent eyes into her ear. "You are too hard upon us. Balzac says, 'All women are not to themselves what no one else is to another.' Do you not agree with him?"

"Cheese it!" says the Princess. "Philosophy palls upon me. I'll shake you."

"Hosses?" says the Count.

Arm and arm they go out to the salon au Beurre.

Armande de Fleury, the young pianissimo danseuse from the Folies Bergère is about to sing.

She slightly clears her throat and lays a voluptuous cud of chewing gum upon the piano as the first notes of the accompaniment ring through the salon

Balzac says, "All women are not to themselves what no one else is to another."

What does this sentence mean?

Oddly