"The four greatest stumbling blocks to understanding are: authority, long-standing custom, the sense of the ignorant crowd, and the hiding of one's own ignorance under the show of wisdom."

"Many errors have crept into the texts of Aristotle, through the ignorance of translators."

"For in the books of the Gentiles, and of the Saracens, and of all unbelievers, there is much that is useful for the understanding of the Scriptures, and for the government of the world, and for the co…"

"The world is full of errors, and men are in darkness, and they do not know it."

"It is better to learn from the infidels than to remain in ignorance."