If you want to be a real seeker of truth, you need to, at least once in your lifetime, doubt in, as much as it's possible, in everything.

What amazes me most is to see that everyone is not amazed at his own weakness.

You see, if the height of the mercury [barometer] column is less on the top of a mountain than at the foot of it (as I have many reasons for believing, although everyone who has so far written about it is of the contrary opinion), it follows that the weight of the air must be the sole cause of the phenomenon, and not that abhorrence of a vacuum, since it is obvious that at the foot of the mountain there is more air to have weight than at the summit, and we cannot possibly say that the air at the foot of the mountain has a greater aversion to empty space than at the top.

When everyone is moving towards depravity, no one seems to be moving, but if someone stops he shows up the others who are rushing on, by acting as a fixed point.

That queen, of error, whom we call fancy and opinion, is the more deceitful because she does not always deceive. She would be the infallible rule of truth if she were the infallible rule of falsehood; but being only most frequently in error, she gives no evidence of her real quality, for she marks with the same character both that which is true and that which is false.

The multitude which is not brought to act as a unity, is confusion. That unity which has not its origin in the multitude is tyranny.

Nothing is more dastardly than to act with bravado toward God.