This revelation consisted of a complete, rational exposition of occult doctrine, from its principles as contained in the mysterious science of numbers to the final consequences of universal evolution, the destiny and end of divine Psyche, the human soul. This science of numbers was known under different names in the temples of Egypt and Asia. As it afforded a key to the whole doctrine, it was carefully concealed from the people. The figures and letters, the geometric forms and human representations, which served as signs in this algebra of the occult world, were understood by none but the initiate. He divulged their meaning to the adepts only after receiving from them the oath of silence. Pythagoras formulated this science in a book he wrote with his own hand, called _hieros logos_ (the sacred word). This book has not come down to us, but we are acquainted with its principles from the subsequent writings of the Pythagoreans, Philolaus, Archytas, and Hierocles, the dialogues of Plato, and the treatises of Porphyry and Iamblichus. The reason they have remained a dead letter for modern philosophers is that their meaning and bearing can only be understood by comparison with all the esoteric doctrines of the East. Pythagoras called his disciples mathematicians, because his higher teaching began by the doctrine of numbers. These sacred mathematics, however, or science of principles, were both more transcendent and more living than profane mathematics, which alone are known to our savants and philosophers. In them Number was not regarded as an abstract quantity but as the intrinsic and active virtue of the supreme One, of God the source of universal harmony. The science of _numbers_ was that of the living forces, _of the divine faculties_ in action in the universe and in man, in the macrocosm and in the microcosm.----In examining them, distinguishing and explaining their working, Pythagoras was evolving nothing less than a rational theogony or theology. In a real theology we should look for the principles of every science; it will be the science of God only if it shows the unity and concatenation of the sciences of nature. It deserves its name only on condition it constitutes the organ and the synthesis of all the rest. Now this is exactly the part played in the Egyptian temples by the science of the holy Word, formulated and made exact by Pythagoras under the name of the science of numbers. It claimed to supply the key of being, of science, and of life. The adept, under the guidance of his master, had to begin by contemplating its principles in the light of his own intelligence, before following its many applications in the concentric immensity of the spheres of evolution.