He's mad that trusts in the tameness of a wolf, a horse's health, a boy's love, or a whore's oath.

I'll follow this good man, and go with you;
And, having sworn truth, ever will be true.

His jest shall savour but a shallow wit, when thousands more weep than did laugh it.

Appetite, a universal wolf.

I essentially am not in madness, but mad in craft.

POLONIUS My lord, the queen would speak with you, and presently.
HAMLET Do you see yonder cloud that's almost in shape of a camel?
POLONIUS By th'mass, and 'tis like a camel indeed.
HAMLET Methinks it is like a weasel.
POLONIUS It is backed like a weasel.
HAMLET Or like a whale?
POLONIUS Very like a whale.
HAMLET Then I will come to my mother by and by. - They fool me to the top of my bent. - I will come by and by.