In The Passions of the Soul (1649) Descartes discarded the Stoic idea that affects are primarily to be dealt with from a moral framework through the application of reason. Instead, he considered affects and emotions neither as good nor bad, but as part of the "aesthetic machine" of the body and as aspects of the soul. What is new is not the concept that emotions, sensations, or affects can be conjoined to the acquisition to new knowledge. After all, this is what Aristotle argued already in the Poetics . What is new is rather the fact that Descartes defines this kind of knowledge in relation to modern epistemology. Revisiting the question of mind–body dualism, Descartes in The  Passions argues that affects may change both our perception of the world and our thoughts about it. The agitation of the mind is not necessarily detrimental to thought; on the contrary, it may enhance or refine  it. Arts that produce emotions allow us to experience new sensations that stimulate the mind. To this end, we need art and literature. By exploring how the theater, fables and poetry may evoke emotions, we can learn what passions are, what they do to us, and how they may serve to produce new knowledge.