...since there can be no tie of direct intercourse to bind the one true God with His creation, and no resemblance whatever can exist between the transient and the Eternal, the contingent and the Absolute, He hath ordained that in every age and dispensation a pure and stainless Soul be made manifest in the kingdoms of earth and heaven. Unto this subtle, this mysterious and ethereal Being He hath assigned a twofold nature; the physical, pertaining to the world of matter, and the spiritual, which is born of the substance of God Himself. He hath, moreover, conferred upon Him a double station. The first station, which is related to His innermost reality, representeth Him as One Whose voice is the voice of God Himself. To this testifieth the tradition: "Manifold and mysterious is My relationship with God. I am He, Himself, and He is I, Myself, except that I am that I am, and He is that He is." ... The second station is the human station, exemplified by the following verses: "I am but a man like you." "Say, praise be to my Lord! Am I more than a man, an apostle?" These Essences of Detachment, these resplendent Realities are the channels of God's all-pervasive grace. Led by the light of unfailing guidance, and invested with supreme sovereignty, They are commissioned to use the inspiration of Their words, the effusions of Their infallible grace and the sanctifying breeze of Their Revelation for the cleansing of every longing heart and receptive spirit from the dross and dust of earthly cares and limitations. Then, and only then, will the Trust of God, latent in the reality of man, emerge, as resplendent as the rising Orb of Divine Revelation, from behind the veil of concealment, and implant the ensign of its revealed glory upon the summits of men's hearts.
From the foregoing passages and allusions it hath been made indubitably clear that in the kingdoms of earth and heaven there must needs be manifested a Being, an Essence Who shall act as a Manifestation and Vehicle for the transmission of the grace of the Divinity Itself, the Sovereign Lord of all.
(Gleanings from the Writings of Baha'u'llah, p. 65)