Nature

Alphabetic literacy changed the way that humans thought of nature. It is the pre-Socratics, the Greeks, and to a lesser extent the Egyptians and Romans, who in their theorizing of nature appear as our kindred spirits, even if we believe their theories are mistaken, in their commitment to rational explanation. A clear line separates pre-alphabetic from post-alphabetic accounts of nature; the mythical accounts of antiquity become topics of derision. Nature increasingly becomes a conceptual entity known only through rational inquiry.

The pre-Socratic philosophers Heraclitus and Parmenides laid down two basic channels in which contemporary ideas still flow. According to Heraclitus (c. 540–c. 480 B.C.E.), reality is a moving river into which humans cannot step twice. And yet, since total chaos would defeat knowability, he posits the strife of opposites as a limit on chaos. Hot becomes cold, wet becomes dry, winter gives way to summer. The wise person behaves according to these basic insights into evanescence and its limits. Heraclitus's notions resonate with contemporary evolutionary thinkers, systems ecologists, and chaos theorists. Chaos theorists celebrate Heraclitus as the conceptual source of a second scientific revolution in the twentieth century. We can also recognize Paleolithic resonances in Heraclitus, including his notion of nature as a cyclical process with which humans should exist in harmony.

Heraclitus's conceptual antagonist was Parmenides (born c. 515 B.C.E.), who argued that reality does not move since "all is one." The apparent motion of nature was for him just that: appearance and not reality. His immediate followers, such as Zeno, devised the famous paradoxes of motion, such as the tortoise and the hare, that conceptually defeated all challenges until the twentieth century. If the tortoise, however slow, starts ahead of the hare, however fast, and if in any given unit of time the hare closes one-half of the distance to the tortoise, the hare can never pass the tortoise because there will always remain an unclosed interval between them. The appearance, then, that the hare catches and passes the tortoise is a deception—"the way of seeming," as Parmenides termed it, and not the "way of truth." The conceptual truths of nature deny perceptual appearances.

The best-known successors to Parmenides are the atomists, Leucippus and Democritus. Perhaps the first truly modern theorists, they corrected Parmenidean conceptual excess. The variety and phenomena of nature were constituted by the arrangement of many "ones"—that is, the atoms themselves. The perceptions of a changing world could now be admitted without undercutting nature's conceptual knowability. Atomic theory today traces its roots to Leucippus and Democritus.