Laudator Temporis Acti

Chamfort:

Society is made up of two great classes: those who have more dinners than appetite, and those who have more appetite than dinners.

Charles Lamb:

The human species, according to the best theory I can form of it, is composed of two distinct races, the men who borrow, and the men who lend. To these two original diversities may be reduced all those impertinent classifications of Gothic and Celtic tribes, white men, black men, red men. All the dwellers upon earth, "Parthians, and Medes, and Elamites," flock hither, and do naturally fall in with one or other of these primary distinctions.

Leopardi:

The human race, from the individual on up, and even in its smallest units, is split into two camps: the bullies and the bullied.

C.S. Lewis:

There are only two kinds of people in the end: those who say to God, "Thy will be done," and those to whom God says, in the end, "Thy will be done." All that are in Hell chose it.

Seen on a t-shirt:

There are 10 types of people in the world: those who understand binary and those who don't.