Invincibility is in oneself, vulnerability in the opponent.

a convincing impossibility is preferable to an unconvincing possibility.

Who then is invincible? The one who cannot be upset by anything outside their reasoned choice.

Who, then, is the invincible human being? One who can be disconcerted by nothing that lies outside the sphere of choice.

A people that has remained convinced of its greatness and invulnerability, that has chosen to believe such a myth in the face of all the evidence, is a people in the grip of a kind of sleep, or madness.

I believe in the incomprehensibility of God.

the unconscious cannot be civilized.

I think anybody incapable of changing his mind is crazy.

You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe

What's all this love of arguing? No one ever convinces anyone else.

how there are never crystallized in them any subjective being-convictions formed by their own logical deliberations — as in general is proper to three-brained beings — but instead, only those convictions are crystallized that depend exclusively upon the opinions of others.

un·shake·able An unwavering and undisputed confidence; a steadfast commitment to the truth; presence, peace of mind, and a calm amidst the storm

for they have no conception how a rational creature can be compelled, but only advised, or exhorted; because no person can disobey reason, without giving up his claim to be a rational creature.

It's very difficult convincing the young of anything. They're born knowing so much.