The ethical treatise "On a Happy Life" ("De vita beata"), which does not survive in its entirety, was written in the late 50s AD and is addressed to Seneca's brother, Novatus, who now bears the new name Gallio; the work takes the form of an apology for the philosopher's way of life - inconsistent, according to the accusations of many.
The main body of Seneca's prose work has a clear philosophical character and, despite the significant influence of the Pythagoreans on his thought, his work constitutes a major source in the history of Stoicism, to which the author gave a more spiritual form and made much more humane.