The antique term “ethopoetic knowledge” designates the kind of knowledge that is able to generate an individual's ethos, i.e. way of life. The notion is revived in the late work of Foucault, who emphasises that also seemingly “objective” knowledge can produce ethical effects. The aim of this paper is to show how Seneca's and Foucault's writings can themselves function as this kind of knowledge; how they, without explicitly pointing to it, provide for the possibility of an ethical attitude. Thus Seneca in his Natural Questions describes nothing but nature, but through this very description the subject can comprehend its own place in the universe. In a similar way, Foucault through his “historical” writings presents the mechanism of discursiv...