“One man is equivalent to all Creation. One man is a World in miniature.”

As quoted in Omni's Screen Flights/Screen Fantasies (1984) edited by Danny Peary, p. 5
General sources

Lecture I. Introductory.
A Treatise on Language: Or, The Relation which Words Bear to Things, in Four Parts (1836)
Context: Man exists in a world of his own creation. He cannot step, but on ground transformed by culture; nor look, but on objects produced by art. The animals which constitute his food are unknown to nature, while trees, fruits, and herbs, are the trophies of his labour. In himself nearly every natural impulse is suppressed as vicious, and every mortification solicited as a virtue. His language, actions, sentiments, and desires are nearly all factitious. Stupendous in achievement, he is boundless in attempt. Having subdued the earth's surface, he would explore its centre; having vanquished diseases, he would subdue death. Unsatisfied with recording the past, he would anticipate the future. Uncontented with subjugating the ocean, he would traverse the air. Success but sharpens his avidity, and facility but augments his impatience.

Source: The World As I See It

#124
1900s, Maxims for Revolutionists (1903)
Source: Man and Superman

Source: The Dharma Bums

The Woman's Bible (1898)

Nur wer einig ist mit der Welt kann einig seyn mit sich selbst.
“Ideas,” Lucinde and the Fragments, P. Firchow, trans. (1991), § 130

Variant translation: There is but one temple in the Universe and that is the Body of Man.
As inscribed on the Library of Congress, quoted in Handbook of the New Library of Congress (1897) by Herbert Small, p. 53
Novalis (1829)
Context: There is but one Temple in the World; and that is the Body of Man. Nothing is holier than this high form. Bending before men is a reverence done to this Revelation in the Flesh. We touch Heaven, when we lay our hand on a human body.

Novalis (1829)