Why?
Because, knowing the value of her wit, she is well aware that it is sufficient by itself to make her a queen in any society.
But a learned woman, a blue-stocking, is not the creature to minister to a man's happiness.

Positive knowledge is not a woman's province.

It is antipathetic to the gentleness of her nature, to the amenity, to the sweet timidity which are the greatest charms of the fair sex, besides, women never carry their learning beyond certain limits, and the tittle-tattle of blue-stockings can dazzle no one but fools.

There has never been one great discovery due to a woman.

The fair sex is deficient in that vigorous power which the body lends to the mind, but women are evidently superior to men in simple reasoning, in delicacy of feelings, and in that species of merit which appertains to the heart rather than to the mind.
Hurl some idle sophism at a woman of intelligence.