  Natural philosophy also incorporates the special sciences, including biology, botany, and astronomical theory. Most contemporary critics think that Aristotle treats psychology as a sub-branch of natural philosophy, because he regards the soul (psuchê) as the basic principle of life, including all animal and plant life. In fact, however, the evidence for this conclusion is inconclusive at best. It is instructive to note that earlier periods of Aristotelian scholarship thought this controversial, so that, for instance, even something as innocuous-sounding as the question of the proper home of psychology in Aristotle’s division of the sciences ignited a multi-decade debate in the  Renaissance.[5] 