Conscientious and careful physicians allocate causes of disease to natural laws, while the ablest scientists go back to medicine for their first principles.
Every art and every inquiry, and similarly every action and choice, is thought to aim at some good; and for this reason the good has rightly been declared to be that at which all things aim.
The seat of the soul and the control of voluntary movement - in fact, of nervous functions in general, - are to be sought in the heart. The brain is an organ of minor importance.
Moral virtue is ... a mean between two vices, that of excess and that of defect, and ... it is no small task to hit the mean in each case, as it is not, for example, any chance comer, but only the geometer, who can find the center of a given circle.
Every formed disposition of the soul realizes its full nature in relation to and dealing with that class of objects by which it is its nature to be corrupted or improved.