Man is a two-legged animal without feathers.

Man is the plumeless genus of bipeds, birds are the plumed.

This world is indeed a living being endowed with a soul and intelligence ... a single visible living entity containing all other living entities, which by their nature are all related.

Hardly any human being is capable of pursuing two professions or two arts rightly.

They do certainly give very strange, and newfangled, names to diseases.

The highest form of pure thought is in mathematics.

Whenever a person strives, by the help of dialectic, to start in pursuit of every reality by a simple process of reason, independent of all sensuous information - never flinching, until by an act of the pure intelligence he has grasped the real nature of good - he arrives at the very end of the intellectual world.