Man becomes aware of the sacred, because it manifests itself, shows itself, as something wholly different from the profane. To designate the act of manifestation of the sacred, we have proposed the term hierophany. It is a fitting term, because it does not imply anything further; it expresses no more than is implicit in its etymological content, i.e., that something sacred shows itself to us. It could be said that the history of religions—from the most primitive to the most highly developed—is constituted by a great number of hierophanies, by manifestations of sacred realities. From the most elementary hierophany—e.g., manifestation of the sacred in some ordinary object, a stone or a tree—to the supreme hierophany (which, for a Christian, is the incarnation of God in Jesus Christ) there is no solution of continuity.
Source: wiktionary
The technical meaning of symbolism is more extensive than the mere assertion that a particular stone or a specific tree is a hierophany. […] Water symbolism involves the common element of water, but lacks a central hierophany such as unites lunar symbolism. […] But there is, for [Mircea] Eliade, an overarching system which implies a meaning which is more comprehensive than any hierophany standing alone, and this system is implied in each particular hierophany.
Source: wiktionary
Hierophany: We have now reached the culminating point of the rite. When the fire bursts forth, the adhvaryu rises, takes away the golden lid and announces: “the gharma is aglow” (rucito gharma). This is one of the key-moments of the whole rite, if not its culminating point. The heat has now reached its Zenith, as also the light which is emitted from the fire. It is in fact the heat which guarantees the hierophany which at this moment takes place in the mahāvira – in the ‘Great Hero’ – which becomes divine. And it is in this highest degree of incandescence that the Sacred appears with all its force and power, assuring its actual divine presence which the sacrifice – sacrum facere – intends to effect and make manifest.
Source: wiktionary
I have found it quite impossible, for example, to discuss the sacred and the coincidentia oppositorum without reference to Eliade’s concept of “hierophany”, and so it is with my attempt to clarify this word that I will begin. Although it may be strange on first exposure this neologism of Eliade’s is deceptively simple. It is compounded, we can easily explain to a freshman student, of the Greek hiero, the holy, the sacred, and phainein, to show. Thus a “hierophany” is a perception of the sacred. […] Despite the clear, simple definitions quoted above, the passive form of the verb, phainesthai, means “to appear”, allowing an interpretation of hierophany as an intransitive action by that which is made manifest — the sacred manifests itself. […] So, not only are things “transformed” into hierophanies, but anything can be so transformed, and yet, having been so transformed the hierophany may remain “cryptic”. Furthermore, “every hierophany makes manifest the coincidence of contrary essences” (Patterns, 29). […] As the Encyclopedia goes on to explain, “the appearance of the sacred in a hierophany, however, does not eliminate its profane existence”.
Source: wiktionary