Unity of opposites

The unity of opposites is the central category of dialectics, said to be related to the notion of non-duality in a deep sense. It is viewed sometimes as either a metaphysical concept, a philosophical concept or a scientific concept. It defines a situation in which the existence or identity of a thing (or situation) depends on the co-existence of at least two conditions which are opposite to each other, yet dependent on each other and presupposing each other, within a field of tension.

First suggested by Heraclitus (ca. 535–475 BC), a pre-Socratic Greek philosopher, philosophers had for some time been contemplating the notion of opposites. Anaximander posited that every element was an opposite, or connected to an opposite (water is cold, fire is hot). Thus, the material world was composed by some indefinite, boundless apeiron from which arose the elements (earth, air, fire, water) and pairs of opposites (hot/cold, wet/dry). There was, according to Anaximander, a continual war of opposites. Anaximenes of Miletus, a student and successor of Anaximander, replaced this indefinite, boundless arche with air, a known element with neutral properties. According to Anaximenes, there was not so much a war of opposites, as a continuum of change. Heraclitus, however, did not accept the milesian monism and replaced their underlying material arche with a single, divine law of the universe, which he called Logos. The universe of Heraclitus is in constant change, but also remaining the same. That is to say, an object moves from point A to point B, thus creating a change, but the underlying law remains the same. Thus, a unity of opposites is present in the universe as difference and sameness. This is a rather broad example though. For a more detailed example we may turn to an aphorism of Heraclitus:

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