Muhyi ad-Din Ibn 'Arabi (1165 - 1240) was an outstanding Spanish-born mystic and one of the most prolific writers in Islamic history. He made major contributions to the fields of Qur'an commentary, jurisprudence, theology, philosophy, cosmology, and spiritual psychology, and he was also a great poet of love. Although he is known as the first spokesman for 'the oneness of being', his real focus was the diverse modalities of human perfection. He marks a transition in Sufism in practical instructions on healing the heart and aphorisms on the divine mysteries to an equal stress on the theoretical issues that had long been the topic of philosophy and theology.