Meanwhile in the mother-country speculation advanced with huge strides. Heraclitus, a descendant of the royal dynasty of Ephesus, withdrew from his democratic fellow-citizens into haughty isolation. Instead of concerning himself with the scientific gossip which tended to make the Ionic _Historia_ lose itself in detail, he laid stress upon the vast concatenation of things. He made the fundamental laws of thought his starting-point, in place of the principles of mathematics. The selection of physical propositions which he deduced poetically from his observations of nature are far more than mere natural symbolism. Fire, constantly transformed into water and earth and as constantly exhaling upwards to the celestial fire, is to him a type of the perpetual change of phenomena that veils the eternal and immutable Law (_logos_), identical in everything but name with the Harmony of the Pythagoreans, which expresses itself in numbers eternally the same. The law of man feeds, he says, upon the divine law manifesting itself in fire. Here we have the germ of the vast scheme of law which binds God and the world, physics and morals, into a compact entity in the Pantheism of the Stoic philosophy. Since he places fire and soul upon the same footing, it follows that human physiology and psychology are explicable by the same formula, to which he likewise ingeniously adapts the Orphic ideas. Thus Heraclitus has exercised great influence upon succeeding generations, and Hegel’s system avowedly leans upon him. Equally great is the influence of Parmenides, the Kant of the ancient world. Descended from an Ionian family of rank which had taken refuge at Elea in Italy at the time of the occupation of Phocæa (560), he carries on the tradition of the philosophic poetry of Xenophanes, whose Pantheistic Monism he defends in acute polemics against the “two-headed” Heraclitus. Being--one, eternal, indivisible, immutable, unchangeable--is alone intellectually conceivable. All beside--multiplicity, divisibility, mobility, variability--is logically inconceivable and therefore non-existent. Reason (_logos_) is consequently the measure of all things. His system is abstract and logical to absurdity, but his postulate that this monistic Being must be bounded like a globe that is equally closed in all directions reminds us that we are still in the age of physics. In him the scepticism of Xenophanes hardens into the assertion that everything which contravenes his logical postulate of the Sole Existent--such as multiplicity, colour, motion, becoming and ceasing to be--is mere illusion.