Heraclitus, Empedocles, and Parmenides all state or suggest that thinking the right kinds of thoughts positively transforms our relationship to our environment. If thoughts are the right kind, it is presumably because they build on the particular receptivity of human nature to true knowledge about the nature of things, knowledge that, in turn, brings the person into greater harmony with the world around him. Thought is thus a uniquely transformative encounter with reality.
Brooke Holmes, The Symptom and the Subject: The Emergence of the Physical Body in Ancient Greece
history, philosophy, psychology