Philosophical systems deriving from Plato (427-347 BCE) in the ancient, medieval, and modern periods. Plato's system was accepted by some religious individuals. In Alexandria, the first-century Jewish thinker Philo sought to create a rapprochement between Platonism and Jewish tradition by using the allegorical method to interpret the Five Books of Moses.
However, this early attempt had no lasting impact on Jewish thought, and it was not until the Middle Ages that the Neoplatonic tradition, created by Plotinus and his successors and filtered through Islamic sources, began to affect Jewish philosophy. The Platonic "forms" were identified with the creative thoughts of God, and God was defined as the Good, the First Principle, and "The One," i.e., as absolutely single and self-sufficient. From this ultimate One, the intelligible world of ideas and the lower forms of being descended or emanated down to the material world (see Sefirot).
The human soul was a particle from a higher realm of being. The Jewish Neoplatonists labeled this higher realm the Throne of Glory, and it was to this that the soul longed to return. Neoplatonism offered a basis not just for rational contemplation but also for spiritual and mystical life. In this system the effort to reunite with the ultimate One lay behind all concrete experience. The methodology to be followed was intellectual abstraction, contemplative ascent in which in the end only God would be left (see Theology).
Isaac Israeli (c. 850-950 CE) is an early source of Jewish Neoplatonism. He defined philosophy as assimilation to God according to the human capacity. Ascent of the human soul to the Divine is through three stages, the ultimate stage depicted as becoming angelic or Divine, an experience to which he applied the word Devekut, conjunction. The Neoplatonic doctrine regarding the unknowability of the first principle is expressed in Israeli's position that only God's existence is knowable and not His essence. This distinction is found in the writings of Baḥya Ibn Pakuda, Joseph Ibn Zaddik, Judah Halevi, and Abraham Ibn Daud.
Another major medieval Neoplatonic Jewish thinker was Solomon Ibn Gabirol, whose doctrines are found in his Mekor Ḥayyim. He stressed that the goal of human existence is the conjunction of the human soul with the supernal world through knowledge and action, specifically intellectual and ethical purification. Ibn Gabirol argued that the study of philosophy offers liberation from death and conjunction with the source of life. The human cannot come to know what Ibn Gabirol labels the "First Essence" because it transcends everything and is incommensurable with the intellect.
In the late Middle Ages, the Republic of Plato became known through the writings of the Arab philosopher Averroes. It was translated into Hebrew by Samuel ben Judah of Marseilles in the 14th century and was widely studied by Jewish thinkers as their introduction to political philosophy. In 1486 Elijah del Medigo translated it into Latin for the Christian mystic Pico della Mirandola. Del Medigo utilized the work in his treatise on faith and reason, Beḥinnat ha-Dat ("An Examination of Faith").
Judah Abravanel, or Leone Ebreo as he was known in Latin, the son of Isaac Abravanel, wove the basic ideas of Platonic philosophy into his Dialoghi di Amore ("Dialogues on Love"). In Moses Mendelssohn's Phaedon, published in 1767, the discussion of the immortality of the soul was modeled on the Platonic dialogue of the same title.
Although Neoplatonism was superseded by Aristotelianism in the development of medieval thought from the 12th century, it continued to have an impact on mystical speculation. The Kabbalah, which came to the fore in the 13th century, was influenced by Neoplatonic thought, including the doctrine of emanation (see Mysticism).
