Iamblichus was a Syrian philosopher who lived in the late 3rd and early 4th centuries CE, from approximately 245 to 325 CE. He was a major figure in the Neoplatonist school of thought. Born into a wealthy family in Chalcis, he studied under Porphyry, a student of the founder of Neoplatonism, Plotinus. Iamblichus later returned to Syria to establish his own influential school.

His writings aimed to create a comprehensive and systematic form of Platonism. His surviving works include On the Pythagorean Life, a biography of Pythagoras; the Protrepticus, an exhortation to study philosophy; and several treatises on mathematics and the mystical properties of numbers. His most famous work is On the Mysteries of the Egyptians (often called De Mysteriis), which defends the use of ritual practice, known as theurgy, as a path to the divine. Many of his other works, including commentaries on Plato and Aristotle, are lost and known only through fragments.

According to modern scholars, Iamblichus is a pivotal figure for moving Neoplatonism in a more religious direction. His most significant contribution was his detailed philosophical justification for theurgy, arguing that ritual acts were essential for the soul's ascent to the divine, a view that contrasted with a focus on pure intellectual contemplation. He also developed a complex hierarchy of divine beings. This "theurgical" Platonism, often called the Syrian School, dominated later Neoplatonic thought and influenced subsequent philosophers, including the Emperor Julian and Proclus.