Alain Danielou on the Phallus as Sacred :
It is only when the penis stands up straight that it emits semen, the source of life. It is then called the phallus, and has been considered, since earliest prehistory, the image of the creative principle, a symbol of the process by which the Supreme Being procreates the Universe.
This is not the case of a symbol plucked at random but the recognition of the continuity of the process that links all the various levels of manifestation, according to cosmological theory. The phallus is really the image of the creator in mankind, and we rediscover the worship of it at the origin of every religion.
A source of pleasure, the phallus evokes divine bliss, the Being of Joy. Within the microcosm of the living being it represents the progenitor, which is always present in its work.
Contempt for this sacred emblem, as well as degradation and debasement of it, pushes man from the divine reality. It provokes the anger of the Gods and leads to the decline of the species. The man who scorns the very symbol of the life principle abandons his kind to the powers of death.
~ Danielou, Alain. The Phallus: Sacred Symbol of Male Creative Power. (1995). Rochester, Vermont: Inner Traditions.