Letters 95.10

And besides, no art that concerns itself with theories can exist without its own doctrines; the Greeks call them dogmas, while we Romans may use the term “doctrines,” or “tenets,” or “adopted principles,”—such as you will find in geometry or astronomy. But philosophy is both theoretic and practical; it contemplates and at the same time acts. You are indeed mistaken if you think that philosophy offers you nothing but worldly assistance; her aspirations are loftier than that. She cries: “I investigate the whole universe, nor am I content, keeping myself within a mortal dwelling, to give you favourable or unfavourable advice. Great matters invite and such as are set far above you. In the words of Lucretius:

Seneca, Letters to Lucilius 95.10, translated by Richard Mott Gummere