In school in the 1970s I learned that the world does not consist only of human beings, trees, cars, colours or even the materials these are composed of; rather, everything is made of tiny, invisible atoms that function according to their own laws. What we perceive and identify in our everyday life emerges from these basic elements that we cannot perceive in ways only the experts know and understand. By the 1970s, atoms were no longer considered indivisible (atomoi), and their more subtle internal structure had been described. Since then, even smaller entities have become the subjects of mainstream physics; these subatomic particles are even further removed from the direct empirical gaze of the perceiver, and from the direct sight of the physicists. Scientists introduce such theoretical entities as quarks and strings to explain the elementary constituents of matter and radiation. For their part, these explicate the true elemental structures of the universe. Importantly for our purposes, the establishment of these new entities has not meant a replacement of, say, an atomic level of explanation, but the opening of a new level of reality and its study. Reality seems to be constituted of a hierarchy of levels, only one of which we are directly aware of.

In late antiquity the philosophical movement called Neoplatonism flourished in cultural centres of the Mediterranean such as Alexandria, Rome and Athens. This school of thought, which prospered from the third century well into the sixth century CE and beyond, shares certain important features with contemporary physics.