INTRODUCTION Ἐκ τῶν οὐρανίων τὰ ἐπίγεια ἤρτηται κατά τινα φυσικήν συμπάθειαν. PHILO, De Opificio Mundi, c. 40. After a long period of discredit and neglect, astrology is beginning to force itself once more on the attention of the learned world. In the course of the last few years scholars have devoted to it profound researches and elaborate publications. Greek man*scripts, which had remained a sealed book at a time when the quest for unpublished documents is all the rage, have now been laboriously examined, and the wealth of this literature has exceeded all expectation. On the other hand, the deciphering of the cuneiform tablets has given access to the wellsprings of a learned superstition, which up to modern times has exercised over Asia and Europe a wider dominion than any religion has ever achieved. I trust, therefore, that I am not guilty of undue presumption in venturing to claim your interest for this erroneous belief, so long universally accepted, which exercised an endless influence on the creeds and the ideas of the most diverse peoples, and which for that very reason necessarily demands the attention of historians. After a duration of a thousand years, the power of astrology broke down when, with Copernicus, Kepler, and Galileo, the progress of astronomy overthrew the false hypothesis upon which its entire structure rested, namely, the geocentric system of the universe. The fact that the earth revolves in space intervened to upset the complicated play of planetary influences, and the silent stars, relegated to the unfathomable depths of the sky, no longer made their prophetic voices audible to mankind. Celestial mechanics and spectrum an*lysis finally robbed them of their mysterious prestige. Thenceforth in that learned system of divination, which professed to discover from the stars the secret of our destiny, men saw nothing but the most monstrous of all the chimeras begotten of superstition. Under the sway of reason the eighteenth and nineteenth centuries condemned this heresy in the name of scientific orthodoxy. In 1824, Letronne thought it necessary to apologise for discoursing to the Academy of Inscriptions on "absurd dreams" in which he saw "nothing but one of those failings which have done most dishonour to the human mind," 1--as though man's failings were not often more instructive than his triumphs. But at the end of the nineteenth century the development of history, from various sides, recalled the attention of investigators to ancient astrology. It is an exact science which was superimposed on primitive beliefs, and when cla**ical philology, enlarging its horizon, brought fully within its range of observation the development of the sciences in antiquity, it could not set aside a branch of knowledge, illegitimate, I allow, but indissolubly linked not only with astronomy and meteorology, but also with medicine, botany, ethnography, and physics. If we go back to the earliest stages of every kind of learning, as far as the Alexandrine and even the Babylonian period, we shall find almost everywhere the disturbing influence of these astral "mathematics." This sapling, which shot up among the rank weeds by the side of the tree of knowledge, sprang from the same stock and mingled its branches with it. But not only is astrology indispensable to the savant who desires to trace the toilsome progress of reason in the pursuit of truth along its doublings and turnings,--which is perhaps the highest mission of history; it also benefited by the interest which was roused in all manifestations of the irrational. This pseudo-science is in reality a creed. Beneath the icy crust of a cold and rigid dogma run the troubled waters of a jumble of worships, derived from an immense antiquity; and as soon as enquiry was directed to the religions of the past, it was attracted to this doctrinal superstition, perhaps the most astonishing that has ever existed. Research ascertained how, after having reigned supreme in Babylonia, it subdued the cults of Syria and of Egypt, and under the Empire,--to mention only the West,--transformed even the ancient paganism of Greece and Rome. It is not only, however, because it is combined with scientific p. xiii theories, nor because it enters into the teaching of pagan mysteries, that astrology forces itself on the meditations of the historian of religions, but for its own sake (and here we touch the heart of the problem), because he is obliged to enquire how and why this alliance, which at first sight seems monstrous, came to be formed between mathematics and superstition. It is no explanation to consider it merely a mental disease. Even then, to speak the truth, this hallucination, the most persistent which has ever haunted the human brain, would still deserve to be studied. If psychology to-day conscientiously applies itself to disorders of the memory and of the will, it cannot fail to interest itself in the ailments of the faculty of belief, and specialists in lunacy will do useful work in dealing with this species of morbid manifestation with the view of settling its etiology and tracing its course. How could this absurd doctrine arise, develop, spread, and force itself on superior intellects for century after century? There, in all its simplicity, is the historical problem which confronts us. In reality the growth of this body of dogma followed a course not identical with, but parallel, I think, to that of certain other theologies. Its starting-point was faith, faith in certain stellar divinities who exerted an influence on the world. Next, people sought to comprehend the nature of this influence: they believed it to be subject to certain invariable laws, because observation revealed the fact that the heavens were animated by regular movements, and they conceived themselves able to determine its effects in the future with the same certainty as the coming revolutions and conjunctions of the stars. Finally, when a series of theories had been evolved out of that twofold conviction, their original source was forgotten or disregarded. The old belief became a science; its postulates were erected into principles, which were justified by physical and moral reasons, and it was pretended that they rested on experimental data ama**ed by a long series of observations. By a common process, after believing, people invented reasons for believing,--"fides quaerens intellectum,"--and the intelligence working on the faith reduced it to formula, the logical sequence of which concealed the radical fallacy. p. xiv There is something tragic in this ceaseless attempt of man to penetrate the mysteries of the future, in this obstinate struggle of his faculties to lay hold on knowledge which evades his probe, and to satisfy his insatiable desire to foresee his destiny. The birth and evolution of astrology, that desperate error on which the intellectual powers of countless generations were spent, seems like the bitterest of disillusions. By establishing the unchangeable character of the celestial revolutions the Chaldeans imagined that they understood the mechanism of the universe, and had discovered the actual laws of life. The ancient beliefs in the influence of the stars upon the earth were concentrated into dogmas of absolute rigidity. But these dogmas were frequently contradicted by experience, which ought to have confirmed them. Then not daring to doubt the principles on which depended their whole conception of the world, these soothsayer-logicians strove to correct their theories. Unable to bring themselves to deny the influence of the divine stars on the affairs of this world, they invented new methods for the better determination of this influence, they complicated by irrelevant data the problem, of which the solution had proved false, and thus there was piled up little by little in the course of ages a monstrous collection of complicated and often contradictory doctrines, which perplex the reason, and whose audacious unsubstantiality will remain a perpetual subject of astonishment. We should be confounded at the spectacle of the human mind losing itself so long in the maze of these errors, did we not know how medicine, physics, and chemistry have slowly groped their way before becoming experimental sciences, and what prolonged exertions they have had to make in order to free themselves from the tenacious grasp of old superstitions. Thus various reasons commended to the attention of scholars these old writings of the Greek astrologers so long neglected. They set to work to re-read and to re-publish these repulsive-looking books which had not been reprinted since the sixteenth century. The last edition--and a shockingly bad one--of the Tetrabiblos of Ptolemy is dated 1581. Further, a number of unknown authors emerged from obscurity, a crowd of p. xv man*scripts mouldering in the tombs of libraries were restored to light. 1 The profit which can be gained from them is not confined to the science of which they treat and to the adjacent domains, which astrology has more or less penetrated. Their utility is much more varied and general, and it would be difficult to set out in full their manifold applications. 2 I shall not dwell on the interest afforded to the scholar by a series of texts spread over more than fifteen centuries, from the Alexandrine period to the Renaissance. Nor, again, will I attempt to estimate the importance which might be claimed in the political sphere by a doctrine which has often guided the will of kings, and decided their enterprises. Nor can I prove here by examples how the propagation of astrological doctrines reveals unsuspected relations between the oldest civilisations, and leads him who traces it from Alexandria and from Babylon as far as India, China, and Japan, bringing him back again from the Far East to the Far West. So many questions of such varied interest cannot be considered all at once. We must exercise restraint and confine ourselves to one view of the subject. Our object in this course of lectures shall be limited to showing how oriental astrology and star-worship transformed the beliefs of the Græco-Latin world, what at different periods was the ever-increasing strength of their influence, and by what means they established in the West a sidereal cult, which was the highest phase of ancient paganism. In Greek anthropomorphism the Olympians were merely an idealised reflection of various human personalities. Roman formalism made the worship of the national gods an expression of patriotism, strictly regulated by pontifical and civil law. Babylon was the first to erect the edifice of a cosmic religion, based upon science, which brought human activity and human relations with the astral divinities into the p. xvi general harmony of organised nature. This learned theology, by including in its speculations the entire world, was to eliminate the narrower forms of belief, and, by changing the character of ancient idolatry, it was to prepare in many respects the coming of Christianity.