For we do not think that we know a thing until we are acquainted with its primary conditions or first principles, and have carried our analysis as far as its simplest elements.
My interest in science was always essentially limited to the study of principles.... That I have published so little is due to this same circumstance, as the great need to grasp principles has caused me to spend most of my time on fruitless pursuits.
Be sincere and true to your word, serious and careful in your actions; and you will get along even among barbarians, But if you are not sincere and untrustworthy in your speech, frivolous and careless in your actions, how will you get along even among your own neighbors? When stand, see these principles in front of you; in your carriage see them on the yoke. Then you may be sure to get along.
The history of science can be viewed as the recasting of phenomena that were once thought to be accidents as phenomena that can be understood in terms of fundamental causes and principles.
Even matter called inorganic, believed to be dead, responds to irritants and gives unmistakable evidence of a living principle within. Everything that exists, organic or inorganic, animated or inert, is susceptible to stimulus from the outside.
He who knows not how to plant his will in things at least endows them with some meaning: that is to say, he believes that a will is already present in them (A principle of faith.)
...virtue is not merely a state in conformity with the right principle, but one that implies the right principle; and the right principle in moral conduct is prudence.