Knowledge is dangerous.

Nothing is more inimical to the progress of science than the belief that we know what we do not yet know.

Belief is the enemy of knowledge.

Nothing puts a greater obstacle in the way of the progress of knowledge than thinking that one knows what one does not yet know.

Knowledge becomes evil if the aim be not virtuous.

Nothing is a greater obstacle to our progress in knowledge, than a bad performance of a celebrated author; because, before we instruct we must begin with undeceiving.

The pride of aiming at more knowledge, and pretending to more perfection, is the cause of Man's error and misery.

The greatest obstacle to discovery is not ignorance — it is the illusion of knowledge.

We are the great danger. Psyche is the great danger. How important is to know something about it, but we know nothing about it.

The only thing more dangerous than an idea is a belief.

All our knowledge brings us nearer to our ignorance.

...as far as we are capable of knowledge we sin in neglecting to acquire it...

Without education, we are in a horrible and deadly danger of taking educated people seriously.

For this fear of death is indeed the pretense of wisdom, and not real wisdom, being the appearance of knowing the unknown; since no one knows whether death, which they in their fear apprehend to be the greatest evil, may not be the greatest good. Is there not here conceit of knowledge, which is a disgraceful sort of ignorance? And this is the point in which, as I think, I am superior to men in general, and in which I might perhaps fancy myself wiser than other men, - that whereas I know but little of the world below, I do not suppose that I know: but I do know that injustice and disobedience to a better, whether God or man, is evil and dishonorable, and I will never fear or avoid a possible good rather than a certain evil.