On 14 December 1914, while saying his prayers at the end of an evening of intensive reading of the Bible and Emanuel Swedenborg, Milosz experienced an illumination that led him to proclaim the next day to a friend: "I have seen the spiritual sun." Influenced by this vision, his poetry became more profound. He began to study the Kabbalah, and Renaissance and Baroque alchemists and thinkers like Paracelsus and Jacob Boehme. After 1916, the development of his metaphysics became his major poetic preoccupation. He began to develop a literary cosmogonic system in the tradition of Lucretius, William Blake, and Edgar Allan Poe and exposed it for the first time in the essay "Épitre à Storge," published in "La Revue de Hollande" in 1917. In the early 1920s, Milosz convinced himself that his poetic cosmogony was supported by Einstein's theory of relativity, still a subject of debate. During this period, after a flirtation with "occult" reading and friends, like the numerologist René Schwaller de Lubicz, Milosz turned his back on these currents of thought and began to study medieval science and thinkers like the English scholastic Robert Grosseteste. Finally, in 1927 he took a Father Confessor and became a practicing Roman Catholic, which he remained for the last twelve years of his life.