Nature is a volume of which God is the author.

It is, however, an argument of no weight to say that natural bodies are first generated or compounded out of those things into which they are at the last broken down or dissolved.

Very many maintain that all we know is still infinitely less than all that still remains unknown.

I profess to learn and to teach anatomy not from books but from dissections, not from the tenets of Philosophers but from the fabric of Nature.

I have often wondered and even laughed at those who fancied that everything had been so consummately and absolutely investigated by an Aristotle or a Galen or some other mighty name, that nothing could by any possibility be added to their knowledge.

And so I conclude that blood lives and is nourished of itself and in no way depends on any other part of the body as being prior to it or more excellent... So that from this we may perceive the causes not only of life in general... but also of longer or shorter life, of sleeping and waking, of skill, of strength and so forth.

There is no perfect knowledge which can be entitled ours, that is innate; none but what has been obtained from experience, or derived in some way from our senses.