 The other Theophrastean treatise in psychology has the title On the Senses or On Sensations (peri aisthēseōn). This work survived for the most part intact and was edited by Hermann Diels, in his Doxographi Graeci (1879), as part of Theophrastus’ Opinions of the Natural Philosophers or Opinions in Natural Philosophy; it was, therefore, treated as a mere source for the physical doctrines of previous philosophers and considered as the origin of the rest of the doxographic tradition. It is rather recently that scholars have eventually recognized it as an independent work, whose study would probably benefit from a new critical edition (see McDiarmid 1962; Baltussen 2019; Mansfeld 2019). More specifically, On the Senses or On Sensations deals with the theories of sense perception put forward by Parmenides, Empedocles, Alcmaeon, Anaxagoras, Cleidemus, Diogenes of Apollonia, Plato and Democritus. It presents and criticizes the views of these philosophers about the senses and their objects, among which vision and colour occupy a central place; it also discusses pain and pleasure, as well as the physiology of thought. Theophrastus applied throughout this work the method of division: The first and main division, already found in Aristotle, is between those who believe sense perception to be by similarity, i.e., in accordance with the principle “like by like”, and those who assume it is through contrast. But another division that is not Aristotelian also plays a part, namely between those who believe that sense perception differs from thought, and those who do not. The last philosopher whom this treatise discusses is Democritus and not Plato, because Democritus argued, in Theophrastus’ view, both that sense perception is by like and that it is by unlike, and so failed to fit the main division (see Mansfeld 1996; Johansen 2019).