Heraclitus was the first philosopher, at least in my mind, who offered an intelligible and insightful perception of the world as a constantly shifting and unstable flux, to which all things will eventually be reclaimed by, with none escaping transformation and destruction. This latter state of affairs also introduces the concept of strife as justice, as while there are no gods to dispense equity, all who are unjust, will eventually be “judged” by the destruction of change, they will not live forever, even if they do manage to kill off the righteous first. The universe as perpetually changing and ultimately out of our control would also inspire the Stoic notion of dividing the mind into things out of our control, and within our control. An individual, who practices this discipline, judging things which are the product of the world’s movements against those which are the product of his own devices, will enjoy wisdom and clarity of perception capable of bringing about true tranquility of spirit, as he will not be afflicted by things which cannot rightly affect him.
It is in this fashion that Heraclitus was perhaps the first philosopher to emphasize practice and an ascetic life rather than philosophy as a science, a tradition which continued up until the time of Descartes, and was especially emphasized by Socrates, the Stoics and Cynics. It is philosophy as a way of life (as Hadot calls it) which is the only good use of philosophy: used as a vessel to temper our misfortunes, to develop good wisdom and virtue and to enable just and excellent action toward other human beings. This calling of philosophy as a lifestyle rather than as a sophist’s payday, is a notion which Heraclitus seems to have introduced, and to whom Socrates, who codified its calling, as well as all of us who bare the fruits of both labors, must be eternally grateful for.