Bad company will lead a man to the gallows! - Niccolò Machiavelli

That which is good for the enemy harms you, and that which is good for you harms the enemy.

"Prudent men are wont to say — and this not rashly or without good ground — that he who would foresee what has to be should reflect on what has been, for everything that happens in the world at any time has genuine resemblance to what happened in ancient times." — Machiavelli

I conclude therefore that, fortune being changeful and mankind steadfast in their ways, so long as the two are in agreement men are successful, but unsuccessful when they fall out. For my part I consider that it is better to be adventurous than cautious, because fortune is a woman, and if you wish to keep her under it is necessary to beat and ill-use her; and it is seen that she allows herself to be mastered by the adventurous rather than by those who go to work more coldly. She is, therefore, always, woman-like, a lover of young men, because they are less cautious, more violent, and with more audacity command her.