The most systematic esoteric interpretation emerged from Rudolf Steiner's extensive lecture series on the Grail delivered 1907-1914, recorded in his Collected Works (particularly GA 149, "Christ and the Spiritual World," and GA 100, "Theosophy and Rosicrucianism").
Steiner taught that the Grail mystery represents "the connection between the Lord of the Earth and the Virgin Mother," brought by "a host of Angels" and maintained "in the realm of the higher Hierarchies." He explicitly connected the Grail tradition to Sophia (Divine Wisdom): "the Divine Sophia, the Divine Wisdom" separated something from herself to maintain vision into the spiritual world. The Grail Maiden represents the feminine aspect of Christ-consciousness.
Rosicrucian training methods described by Steiner involved imaginative meditation: students contemplated "the plant's calyx" compared to human generative organs, leading to the image of the "Holy Grail, the passionless chalice." This represents purified human nature transformed from "sex filled with passion" to spiritual receptivity. "This is the deeper meaning of the Holy Grail, which was brought to the knowledge of the Rosicrucian students."