Yesod is the ninth sephira of the Tree of Life discussed in the Kabbalah, it is the symbol of pure life. Often synonymous with deprivation and self-control that lead to oppression and poverty or even perversion, purity has been a premature death of the individual. What the Teacher Omraam Mikhaël Aïvanhov shows us, taking a stand against this partial and mistaken perception of purity, presents it, on the contrary, as a world of extremely rich and creative life, still unknown and unexplored, based on an accurate knowledge of psychic and spiritual life. Taking purity as the foundation of his spiritual Teaching (Yesod in Hebrew means "foundation", "pillar"), Teacher Omraam Mikhaël Aïvanhov rediscovers the meaning of the applications of the ancient Initiations, which he enriches with many discoveries he himself made. The rules and exercises he gives and that he himself experimented with for a long time, free man and awaken within his entire existence the emerging and harmonious forces of divine life. In this book on the Mysteries of Yesod, Teacher Omraam Mikhaël Aïvanhov makes us feel how the life of a spiritual Teacher is similar to this "river of life" that purifies all those who approach it.