Alexander Aphrodisius said that there are three causes which prevent men from discovering the exact truth: first, arrogance and vainglory; secondly, the subtlety, depth, and difficulty of any subject which is being examined; thirdly, ignorance and want of capacity to comprehend what might be comprehended.

The discovery of this reality is hindered rather than helped by belief, whether one believes in God or believes in atheism.

Nothing limits intelligence more than ignorance; nothing fosters ignorance more than one's own opinions; nothing strengthens opinions more than refusing to look at reality.

The inclination to seek the truth is safer than the presumption which regards unknown things as known.

Prejudice saves us a painful trouble, the trouble of thinking.

Undoubtedly it is our duty, and for our best good, that we occupy and improve the faculties, with which our creator has endowed us, but so far as prejudice, or prepossession of opinion prevails over our minds, in the same proportion, reason is excluded from our theory or practice. Therefore if we would acquire useful knowledge, we must first divest ourselves of those impediments and sincerely endeavor to search out the truth: and draw our conclusions from reason and just argument, which will never conform to our inclination, interest or fancy; but we must conform to that if we would judge rightly.

So hard is it to discover the truth, because the history of past ages is rendered difficult by the lapse of time; while in contemporary history the truth is always obscured, either by private spite and hatred, or by a desire to curry favour with the chief men of the time.

To believe something strongly when it is clearly hard to define and prove, and has not been proven, is to be prejudiced.

PREJUDICE, n. A vagrant opinion without visible means of support.

It is indeed like that, how often we are held by prejudice, so that we either do not admit what is before our eyes or bow as much as possible to a preconceived opinion because of the perverse wont of human nature. Nor do I except myself from that weakness.

The number one thing clouding us from being able to see reality is we have preconceived notions of the way it should be.

It is well known, that, in all questions submitted to the understanding, prejudice is destructive of sound judgment, and perverts all operations of the intellectual faculties: it is no less contrary to good taste; nor has it less influence to corrupt our sentiment of beauty. It belongs to good sense to check its influence in both cases.

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

False and doubtful positions, relied upon as unquestionable maxims, keep those who build on them in the dark from truth. Such are usually the prejudices imbibed from education, party, reverence, fashion, interest, et cetera.