There are five billion people living on this planet. But you fall in love with one particular person, and you won't swap her for any other.

What Plato was really asking was perhaps why a horse was a horse, and not, for example, a cross between a horse and a pig.

A hydrogen atom in a cell at the end of my nose was once part of an elephant's trunk. A carbon atom in my cardiac muscle was once in the tail of a dinosaur.

When you realize there is something you don't understand, then you're generally on the right path to understanding all kinds of things.

Maybe we can comprehend a flower or an insect, but we can never comprehend ourselves. Even less can we expect to comprehend the universe.

That fact that Athens could condemn its noblest citizen to death did more than make a profound impression on him. It was to shape the course of his entire philosophic endeavor.

We can't own each other's past. The questioin is whether we have a future together.