Xenophanes’ date is uncertain between c 570 - 475 BCE. He was from Colophon, a city in the region of Lydia, but lived most of his life in southern Italy. He lived in between the times of Pythagoras and Heraclitus. This is concurred as he alludes to Pythagoras and Heraclitus alludes to him.
Xenophanes philosophy shows a streak of skepticism. He satirized the polytheistic beliefs of the Greeks. He believed in one God and considered it as formless. He argued that if Horses and Cows could paint they would paint God as themselves just like Humans give a humanly form to god. The Ethiopian God is black and the Thracian god is blue eyed with red hairs. Xenophanes is often seen as one of the first monotheists, in the Western philosophy of religion.
His epistemology held that there exists a truth of reality, but that humans as mortals are unable to know it. Therefore, it is possible to act only on the basis of working hypotheses - we may act as if we knew the truth, as long as we know that this is extremely unlikely. This aspect of Xenophanes is the basis of Critical rationalism. Xenophanes can be considered the first amongst the rationalists.
Xenophanes ridiculed Pythagoras’ theory of transmigration. Xenophanes considered that all things are made up of earth and water.
Heraclitus flourished around 500 B.C. He was citizen of Ephesus in Ionia. Though an Ionian, he didn’t belong to the scientific schools of Miletus. From the solitary and melancholic life he led, and still more from the riddling nature of his philosophy and his contempt for humankind in general, he was called "The Obscure," and the "Weeping Philosopher." He was a mystic of different type. He regarded fire as the primordial substance. He is famous for his doctrine of flux and doctrine of strife.
Doctrine of Flux: The doctrine that everything is in the state of flux is most famous of Heraclitus.
“This world, which is same for all, no one of gods or men has made; but it was ever, is now, and ever shall be an ever living fire, with measures kindling and measures going out. The transformed fire are , first of all, sea, and half of the sea is earth, half whirlwind.”
Such a world, Heraclitus believed, is always in a state of flux.
“You cannot step twice into the same river ; for fresh waters are ever flowing in upon you.”
Doctrine of Strife: This doctrine is about mingling of opposites to create harmony. “Men do not know”, he says, “how what is at variance agrees with itself. It is and attunement of opposite tensions, like that of bow and lyre”. His belief in strife is connected with this theory, for in strife opposite combines to produce motion which is in harmony. There is unity in the world, but it is unity resulting from diversity. This doctrine contains the germ of Hegel’s Philosophy, which proceeds by synthesizing of opposites. The metaphysics of Heraclitus, like that of ‘Anaximander’ is dominated by a conception of cosmic justice, which prevents the strife of opposite from ever issuing in the complete victory of either.
Heraclitus’s ethics is a kind of proud asceticism, very similar to Nietzsche’s. He regards the soul as a mixture of fire and water, the fire being the noble and the water being ignoble. The soul that has most fire he calls “dry”. “The dry soul is the wisest and the best”. It is pleasure to soul to become moist. It is death to soul to become water.