Human history is in essence a history of ideas.

There is no come back to caves. We are too many.

The people who turn out best are those people who make the best out of the way things turn out.

I like university professors, but you know, we shouldn't hold them up as the high-water mark of all human achievement. They're just a form of life, another form of life.

Cultivation of mind should be the ultimate aim of human existence.

I despise people who depend on these things [heroin and cocaine]. If you really want a mind-altering experience, look at a tree.

Every form of addiction is bad, no matter whether the narcotic be alcohol, morphine or idealism.

Ninety-nine percent of who you are is invisible and untouchable.

Man has the power to act as his own destroyer - and that is the way he has acted through most of his history.

There seems to be some perverse human characteristic that likes to make easy things difficult.

Ever more people today have the means to live, but no meaning to live for.

Challenging the meaning of life is the truest expression of the state of being human.

You climb to reach the summit, but once there, discover that all roads lead down.

Family not only need to consist of merely those whom we share blood, but also for those whom we'd give blood.

The first time someone shows you who they are, believe them.

Some people seem to fade away but then when they are truly gone, it's like they didn't fade away at all.

I just invent, then wait until man comes around to needing what I've invented.

Of mankind we may say in general they are fickle, hypocritical, and greedy of gain.

Though I love my country, I do not love my countrymen.

The first human who hurled an insult instead of a stone was the founder of civilization.

There are four million different kinds of animals and plants in the world. That’s four million solutions to the problem of staying alive.