Chapter 6 explores the interconnection between natural philosophy and liberation from rebirth, arguing first that knowledge of the world is necessary to change one’s being from mortal to divine nature and, second, that purifications play a central role in knowledge acquisition. After a consideration of epistemic reflections at Empedocles’ time and the role of initiation in attaining true knowledge, it is shown that Empedocles explains the change of being into divine nature at the level of the elements. Indeed, in processes of perception and knowledge acquisition, elements coming from external effluvia interact with elements in the body and thereby modify the mind’s mixture. It follows that the revelation of Empedocles’ philosophy can change our mind to the point that it will become a divine mind. The possibility of becoming divine through knowledge of the world goes along with the training one must undergo to be adequately prepared to receive it. This training coincides with processes of purification, and Empedocles explains from a physiological standpoint how these enable the structure of the elements of our mind to be enhanced to the point where it becomes attuned to the divine.

This chapter uses three secondhand reports (the testimonies on Petron and Philistion in the Anonymus Londiniensis, the speech of Eryximachus in Plato’s Symposium, and the treatise On Ancient Medicine) to point out that an interest in cosmological principles does not preclude more traditional explanations of health and disease. Petron, Philistion, and Eryximachus all combine their first principles with lower-level discussions of the humors, pneuma, and the “powers” of food and drink. Instead of replacing humors with cosmic principles, these doctors constructed multitiered narratives of pathogenesis, placing humors and cosmic principles at different points in the causal chain. After making this point, this chapter then demonstrates that the polemical On Ancient Medicine is an unreliable witness to what the cosmological doctors were doing. Whereas the author of this text claims that the prioritizing of such principles as the hot and the cold is incompatible with the attribution of diseases to the humors, the cosmological doctors were in fact more than comfortable with combining first principles with more traditional beliefs about the body.

Ancient Greece provided the setting for the first detailed, recorded hypotheses about the causes of human activity. In the search for first principles of life, tentative explanations included: The naturalistic orientation of the Ionian physicists Democritus, Heraclitus, and Parmenides looked to some basic physical element in nature as this first principle. A biological orientation, developed by Alcmaeon, Hippocrates, and Empedocles, held that bodily physiology is the key. Pythagoras held that life is transcendent of the material world and found in the essential coherence of mathematical relationships. The Sophists posited a pragmatic orientation that denied the value of trying to seek out first principles, relying instead on observations of life as it is lived. Finally, Anaxagoras and Socrates, rejecting the Sophists, proposed the existence of a soul that defines humanity. This humanistic orientation developed the notion of the spiritual soul that possesses the unique human capabilities of the intellect and the will. The soul was elaborated as the central element in the interpretation of life offered by Plato and Aristotle. By the end of the Greek era the critical themes and issues of psychology as well as the methodological approaches were well identified and structured.