Cavendish has a lot of logic but it is not argumentative logic; it is wit-logic, and wit-logic was a sign of goodness. When she wrote about wit in the Sociable Letters (1664), it was as if she wrote about intelligence itself. “Wit and Fools can never agree, they understand not one another; Wit flies beyond a Fools conceit or understanding, for Wit is like an Eagle, it hath a strong wing, and flies high and far, and when it doth descend, it knocks a Fool on the head, as an Eagle doth a Dotril, or a Woodcock, or such like Birds; and surely the world was never so fill'd with Fools, as it is in this age […] It is not an age like Augustus Caesar's when Wisdom reign'd and Wit flourished, which was the cause of Plenty & Peace throughout the whole world” (Letter 7).
Wit is a powerful property, wit is enviable, “Wealth, Merit, Power, or Wit,” (Letter 31), “Learning, or Judgment, or Wit, or Conceptions, or Understanding” (Letter 161), “Prudent, Just, Valiant, Generous, Understanding, Judicious, Witty, and Wise” (Letter 135), “Wit and Wisdom” (Letter 79), “for that which is Best and Good, is not General, especially Wit, for the Right True and Best Wit keeps to Particulars, as being Understood by Particulars” (Letter 63). She is never rude about wit.
She is not likely to put Wit next to war, although in other places she will admire a man who is willing to fight; most of the other nouns she sees next to Wit are intangible social assets, mainly Wisdom.
Her wit is Shakespeare-wit, it is word-logical and idea-logical, and with this logic she draws distinctions and she writes like a dance; you restrict yourself with steps and inside those steps you demonstrate your ideas. You are blurred between restriction and expansion. You are dictating the steps, the steps are dictating you, and both things are happening. When the letter-writer wants her recipient to forgive her for not writing when she has no news, she does it with wit: “my Letter will be like a Bladder fill'd with Wind, and not like a Bag fill'd with Gold or Silver; or they will be like Paper that is only fill'd with Cifres, without any Figures; But although my Letters may be as Cifres, yet you, to whom I write, are the Chief Figure in my Thoughts, which Expresses Thousands; indeed, you are as Infinite it self, for your Merits are Numberless, and there is no End of your Goodness, for which Eternal Happiness will be your Reward in Heaven.” (I've lost the letter number.)
She is often witty when she is apologising or depreciating herself (Letter 131).
At other times she will stay with an idea and pile up lists of inventions. In Letter 193 she is going through a freezing winter: "every Hair stands out like a Squadron of Pikes, to Resist Cold's Assault; and Ammunition of Coals serves for Bullets, and Ashes for Power, with great Loggs for Cannons, Billets for Muskets and Carbines, Brush Faggots for Pistols, where the Bellows as Firelocks, makes them fly up in a Flame; also great Pieces of Beef for Ships for Men of War, with Cabbages for Sails, Sausages for Tacklings, Carrots for Guns, and Marrow-Bones for Masts, Ballasted with Pepper, and Pitch'd or Tarr'd with Mustard ...” (Letter 190).
“Some Moders have oftener Wit in their Mouths than in their Brains, that is, they Speak the Wit of Others but have none of their Own” (Letter 63). Wit, for her, is a sign of active imagination. She refutes people who criticise Shakespeare because he writes undignified characters, “Clowns, Fools, Watchmen, and the like” (Letter 123), for
it Expresses and Declares a Greater Wit, to Express and Deliver to Posterity, the Extravagances of Madness, the Subtilty of Knaves, the Ignorance of Clowns, and the Simplicity of Naturals, or the Craft of Feigned Fools, than to express Regularities, Plain Honesty, Courtly Garbs, or Sensible Discourses, for 'tis harder to Express Nonsense than Sense, and Ordinary Conversations than that which is Unusual …
“What Cavendish has to say about Shakespeare is strikingly modern and quite out of keeping with the time in which Sociable Letters was published,” wrote the Cavendish scholar James Fitzmaurice. “Cavendish is not merely the first woman to launch a serious and sustained critique of Shakespeare, she is the first person to do so.” This is from the introduction to the Garland edition of Sociable Letters, 1997. It could be that her love of Wit and the qualities that she sees associated with Wit, have led her to both the Shakespeare critique and the “wildest fancies” observed by Virginia Woolf.