This book includes several works by the famous thinker and researcher of religious traditions Rene Guenon (1886-1951), including the book "Principles of Infinitesimal Calculus," dedicated to the connection of mathematical symbolism with the traditional "science of numbers." We are talking about a branch of knowledge that has found its reflection in Pythagorean numerology, in Hebrew Kabbalah, in the doctrine of the number of Alexandrian Neoplatonism, in other religious and philosophical teachings of antiquity, which widely used numerical and geometric symbolism.