The Eleusinian Mysteries, dedicated to Demeter and Dionysus, are a divine thaumaturgy handed down by Demeter herself to humanity, which revealed to them the path (progress) of the mind, representing the essence of the soul in matter, its stay there within a cycle of incarnations of life and death (maturation), and ultimately its return to the Principle, from which it emanates (return), leading to the deification of man and the immortality of the soul.

In the sacred rites of Eleusis, initiates became "perfected," experiencing the transcendence of death. Dionysus-Iacchus, the leader of the Mysteries, guides this revealing journey of the soul, which descends into our Underworld (Persephone) and cares for its essence (Kore); and whoever is initiated into its Mysteries, as Pindar says, knows the end of life-death and the beginning of life, the gift of Dionysus: "he knows the end of life, but knows not the divine beginning," which was bound to secrecy under threat of death.

The Mysteries had an ethical and pedagogical dimension and made the initiates virtuous and better in every way: "for the best of themselves." This book provides etymological interpretations of codes, names, words, and phrases, such as those related to divine oversight, the second degree of initiation, in an effort to philosophically approach the processes of nature, which are paralleled with those of the soul.

The entire journey of the Sacred Way and the significant stations of the Iacchus procession correspond to the ontological journey of the soul within matter. Topics such as the mourning and laughter of the Gods, copper as the metal of demons, the sacred symbols of the spike and the poppy, their mystical symbolism, and the snakes of Demeter's chariot of dragons are also discussed, along with their relation to Triptolemus and how they reflect the latest theories of Quantum Physics regarding electromagnetism and the creation of mass.

The Temple of Eleusis fell silent with the advent of a new religion, and as Nestorius, the last Hierophant of Eumolpus, said, it was "the beginning of the great spiritual darkness of humanity," because "blessed is he who saw these things with his own eyes among mortals, but the uninitiated and uninvolved in sacred matters have no such fate, for they are lost beneath the mists and moldy darkness." (Homer, Hymn to Demeter, vv. 480-482)