Theosophy Basics: The Microcosm and Macrocosm Analogy - Macrocosm and Microcosm Correspondence

The classic work on the subject (albeit in a skeptical mode) is George P. Conger's Theories of Macrocosms and Microcosms in the History of Philosophy (1922) where he shows how this concept is common to many esoteric traditions such as Neoplatonism, the Kabbalah, Sufism, and philosophers and occultists such as Nicholas of Cusa, Giordano Bruno, Paracelsus, and Jacob Boehme.

According to Antoine Faivre two main types of correspondences exist:

a) those in nature (between microcosmic and macrocosmic entities such as the planets and parts of the body or those that exist in astrology) and

b) those that exist between revealed texts (and history) and Nature such as the correspondence between the Bible and Nature as represented in the Kabbalah. (Antoine Faivre, Access to Western Esotericism, 10-15 (Albany: SUNY, 1994)

G.R.S. Mead outlines the concept in the Neoplatonic schools:

The whole of Orphic psychology was based on the axiom that man has in him potentially the sum and substance of the universe. Everything was ensouled, there was no spot in the universe without life of some kind (πἃν εἳναι σὣμα ἔμψυχον — Philoponus, De An., i). And again, 'the race of men and gods is one' (Pindar, who was a Pythagorean, quoted by Clemens, Strom., V.709). Thus the universe was an 'animal' or thing 'ensouled'. The sun is its heart, the moon its liver, and so on (Plutarch, De Fac. Lun., xv).
Thus man was called the microcosm or little world, to distinguish him from the universe or great world. Hence we find man referred to as the 'little animal' ( ζὣον μικρόν – Galen, De Usu Part., iii. 10); the 'little world' (ἄνθρωποϛ βραχὺϛ κόσμοϛ ) – Philo, De Vit. Mos., iii.673, D), or 'little heaven' (Philo, De Mund. Optif, p. 18, E); the 'little diacosm' ( μικρὸν διάκοσμον– Porphyry, Stob., Serm., xxi.185); the 'lesser world' (minorem mundum – Solin., c. v.); and so on. And as man was the Little Universe, so the universe was the Great Man (Philo, Quis Rer. Div. Haer., p. 502, C).

Thus we find Proclus (Tim., i.348) telling us that we must view man as the little universe, 'for he has both a mind and a reason (logos), a divine body and a perishable body, like the universe; in fact his whole constitution bears an analogy with the universe. (Orpheus, 175) 
This concept can be found in Eastern traditions as well, for example in India and China:

The universe consists of a Mahābrahmānda, or grand Cosmos, and of numerous Brhatbrahmānda, or macrocosms evolved from it. As is said by the Nirvāna- Tantra, all which is in the first is in the second. In the latter are heavenly bodies and beings, which are microcosms reflecting on a minor scale the greater worlds which evolve them. “As above, so below.” The mystical maxim of the West is stated in the Viśvasāra-Tantra as follows: “What is here is elsewhere; what is not here is nowhere” (yadhihāsti tadanyatra yannehāsti na tatkvacit). …

The witness within is the purusa without, for the personal soul of the microcosm corresponds to the cosmic soul (hiranyagarbha) in the macrocosm. (Arthur Avalon, Mahanirvana Tantra, Introduction, 22, 1913)

In the interpretation of the following translation, it is of value to say a few more words about the foundations of the Weltanschauung on which the method depends. This philosophy is, to a certain extent, the common property of all Chinese trends of thought. It is built on the premise that cosmos and man in the last analysis obey common laws; that man is a cosmos in miniature and is not divided from the great cosmos by any fixed limits. The same laws rule for the one as for the other, and from the one a way leads into the other. The psyche and the cosmos are related to each other like the inner and outer worlds. Therefore man participates by nature in all cosmic events, and is inwardly as well as outwardly interwoven with them. Tao, then, the meaning of the world, the way, dominates man just as it does invisible and visible nature (Heaven and Earth). (Richard Wilhelm, Discussion, 2, 11 The Secret of the Golden Flower, 1931)

H. P. Blavatsky describes this notion as follows:

Man is a little world — a microcosm inside the great universe. Like a foetus, he is suspended, by all his three spirits, in the matrix of the macrocosmos; and while his terrestrial body is in constant sympathy with its parent earth, his astral soul lives in unison with the sidereal anima mundi. He is in it, as it is in him, for the world-pervading element fills all space, and is space itself, only shoreless and infinite. (Isis Unveiled, Vol. I, pp. 212)

The Universe is worked and guided from within outwards. As above so it is below, as in heaven so on earth; and man — the microcosm and miniature copy of the macrocosm — is the living witness to this Universal Law, and to the mode of its action. We see that every external motion, act, gesture, whether voluntary or mechanical, organic or mental, is produced and preceded by internal feeling or emotion, will or volition, and thought or mind. As no outward motion or change, when normal, in man’s external body can take place unless provoked by an inward impulse, given through one of the three functions named, so with the external or manifested Universe. The whole Kosmos is guided, controlled, and animated by almost endless series of Hierarchies of sentient Beings, each having a mission to perform, and who — whether we give to them one name or another, and call them Dhyan-Chohans or Angels — are “messengers” in the sense only that they are the agents of Karmic and Cosmic Laws. (Secret Doctrine Vol. .I , 274)