“Within that awful volume lies
The mystery, of mysteries!”

Source: Morals and Dogma of the Ancient and Accepted Scottish Rite of Freemasonry (1871), Ch. XXII : Grand Master Architect, p. 190

Source: A Natural History of the Senses (1991)

Life Is A Miracle : An Essay Against Modern Superstition (2000)
Context: We are alive within mystery, by miracle. "Life," wrote Erwin Chargaff, "is the continual intervention of the inexplicable." We have more than we can know. We know more than we can say. The constructions of language (which is to say the constructions of thought) are formed within experience, not the other way around. Finally we live beyond words, as also we live beyond computation and beyond theory. There is no reason whatever to assume that the languages of science are less limited than other languages.

Source: The Sayings and Teachings of the Great Mystics of Islam (2004), p. 270

" The Life and Teachings of Thoth Hermes Trismegistus http://magdelene.net/Thoth%20Hermes%20Trismegistus.htm", in The Secret Teachings of All Ages (1928) by the Canadian occultist Manly Hall; a few quotation websites credit this to Addison.
Misattributed

Life Is A Miracle : An Essay Against Modern Superstition (2000)

Source: Tao Te Ching, Ch. 1, Gia-Fu Feng & Jane English (1972)
Context: The Tao that can be told is not the eternal Tao;
The name that can be named is not the eternal name.
The nameless is the beginning of heaven and earth.
The named is the mother of ten thousand things.
Ever desireless, one can see the mystery.
Ever desiring, one can see the manifestations.
These two spring from the same source but differ in name;
this appears as darkness.
Darkness within darkness.
The gate to all mystery.

Fragment No. 16
Variant translations:
We dream of a journey through the universe. But is the universe then not in us? We do not know the depths of our spirit. Inward goes the secret path. Eternity with its worlds, the past and the future, is in us or nowhere.
As translated in "Bildung in Early German Romanticism" by Frederick C. Beiser, in Philosophers on Education : Historical Perspectives (1998) by Amélie Rorty, p. 294
We dream of journeys through the cosmos — Is the cosmos not then in us? We do not know the depths of our own spirit. — The mysterious path leads within. In us, or nowhere, is eternity with its worlds — the past and the future.
Blüthenstaub (1798)
Context: Imagination places the future world for us either above or below or in reincarnation. We dream of travels throughout the universe: is not the universe within us? We do not know the depths of our spirit. The mysterious path leads within. In us, or nowhere, lies eternity with its worlds, the past and the future.