In 1900, Alan Leo gave four foundational lectures on inner astrology, in front of the audience of the Theosophical Society of London, inaugurating a new era for the external and internal structure and usefulness of art in various areas of life.[...] The one who undertook the gigantic task of classifying, testing, or rejecting this material, for the sake of all future generations of astrologers, was Alan Leo, and we can say that in this work his internal perspective on astrology is described clearly, as well as his far-sighted vision for its future development.