Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows, griefs, despondency, and lamentations. And by this, in an especial manner, we acquire wisdom and knowledge, and see and hear and know what are foul and what are fair, what are bad and what are good, what are sweet and what are unsavory…. And by the same organ we become mad and delirious, and fears and terrors assail us….All these things we endure from the brain when it is not healthy….In these ways I am of the opinion that the brain exercises the greatest power in the man.

There are, in effect, two things, to know and to believe one knows; to know is science; to believe one knows is ignorance.

Let your food be your medicine, and your medicine be your food.

To really know is science; to merely believe you know is ignorance.

Foolish the doctor who despises the knowledge acquired by the ancients.

...all the most acute, most powerful, and most deadly diseases, and those which are most difficult to be understood by the inexperienced, fall upon the brain.

I have clearly recorded this: for one can learn good lessons also from what has been tried but clearly has not succeeded, when it is clear why it has not succeeded.