“Every fool knoweth that hatreds are the cinders of affection.”
— Letter to Sir Robert Cecil (10 May 1593)
“A prince of mean force ought not in any wise to adventure his estate upon one day's fight: for if he be victorious he gaineth nothing but glory; but if he lose, he is utterly ruined.”
— Aphorisms of State (London: for Tho. Johnson, 1661), p. 101
“Be advised what thou dost discourse of, and what thou maintainest whether touching religion, state, or vanity; for if thou err in the first, thou shalt be accounted profane; if in the second, dangerous; if in the third, indiscreet and foolish.”
— Chapter IV
“It is the nature of men, having escaped one extreme, which by force they were constrained long to endure, to run headlong into the other extreme, forgetting that virtue doth always consist in the mean.”
— Chapter 25
“Whoso desireth to govern well and securely, it behoveth him to have a vigilant eye to the proceedings of great princes, and to consider seriously of their designs.”
— Chapter 25
“What dependence can I have on the alleged events of ancient history, when I find such difficulty in ascertaining the truth regarding a matter that has taken place only a few minutes ago, and almost in my own presence!”
— Upon receiving discrepant accounts from the participants in a recent quarrel below his window.

Quotes via Wikiquote (CC BY-SA), each with its original source.