If you find from your own experience that something is a fact and it contradicts what some authority has written down, then you must abandon the authority and base your reasoning on your own findings.

When counting, try not to mix chickens with blessings.

Poor is the pupil who does not surpass his master.

A clever man without wisdom is like a beautiful flower without fragrance.

We must doubt the certainty of everything which passes through the senses, but how much more ought we to doubt things contrary to the senses, such as the existence of God and the soul.

An artist who lacks the power of self-criticism accomplishes but little. It is good if your work stands higher than your own opinion of it; bad if it is on the same level. But it is a great disaster if your work stands lower than your judgment of it.

A diamond is just a lump of coal that stuck to its job.