  While some later medieval Jewish thinkers—such as Shem Tov Ibn Falaquera, Moses Ibn Ezra, Abraham Ibn Daud, Joseph ibn Zaddik and Isaac and Judah Abrabanel—were familiar with his philosophy, Ibn Gabirol is probably most well-known among medieval and modern Jewish authors for his Hebrew poetry, the best known of which being the Keter Malkhût (variously translated as Kingdom's Crown, The Kingly Crown, The Royal Crown, et  al.),[14] a long devotional poem exploring the ineffable splendor of the divine and tracing God's presence throughout the various cosmological spheres which make up the universe. In fact, this poem is included in many Jewish prayer books for recitation on Yôm Kippûr (The Day of Atonement), the highest of Jewish holy days.