[...] The basis of Iamblichus' philosophy was Neoplatonism and the theoretical teachings of Plotinus, which he generally followed. However, he made several changes to the Neoplatonic system, mainly in his attempt to revive Pythagorean numerology. For Iamblichus, number is the soul of the world, and the theory of Ideas is intertwined with the mysticism of numbers. From this perception, which almost deifies numbers, Iamblichus (like Pythagoras before him) developed a strong interest in mathematics. Iamblichus' numerological interpretation of the world was greatly influenced by earlier Neopythagoreans, such as Anatolius and Nicomachus of Gerasa. [...]
(from the introduction of the book)