This way of reasoning was universally considered irrefutable. Before the advent of Christianity, which especially opposed it because of its idolatrous character, astrology had scarcely any adversaries except those who denied the possibility of science altogether, namely, the neo-Academicians, who held that man could not attain certainty, and such radical sceptics as Sextus Empiricus. Upheld by the Stoics, however, who with very few exceptions were in favor of astrology, it can be maintained that it emerged triumphant from the first assaults directed against it. The only result of the objections raised to it was to modify some of its theories. Later, the general weakening of the spirit of criticism assured astrology an almost uncontested domination. Its adversaries did not renew their polemics; they limited themselves to the repetition of arguments that had been opposed, if not refuted, a hundred times, and consequently seemed worn out. At the court of the Severi any one who should have denied the influence of the planets upon the events of this world {168} would have been considered more preposterous than he who would admit it to-day. But, you will say, if the theorists did not succeed in proving the doctrinal falsity of astrology, experience should have shown its worthlessness. Errors must have occurred frequently and must have been followed by cruel disillusionment. Having lost a child at the age of four for whom a brilliant future had been predicted, the parents stigmatized in the epitaph the "lying mathematician whose great renown deluded them."[14] Nobody thought of denying the possibility of such errors. Manuscripts have been preserved, wherein the makers of horoscopes themselves candidly and learnedly explain how they were mistaken in such and such a case, because they had not taken into account some one of the data of the problem.[15] Manilius, in spite of his unlimited confidence in the power of reason, hesitated at the complexity of an immense task that seemed to exceed the capacity of human intelligence,[16] and in the second century, Vettius Valens bitterly denounced the contemptible bunglers who claimed to be prophets, without having had the long training necessary, and who thereby cast odium and ridicule upon astrology, in the name of which they pretended to operate.[17] It must be remembered that astrology, like medicine, was not only a science ([Greek: episteme]), but also an art ([Greek: techne]). This comparison, which sounds irreverent to-day, was a flattering one in the eyes of the ancients.[18] To observe the sky was as delicate a task as to observe the human body; to cast the horoscope of a newly born child, just as perilous as to make a diagnosis, and to interpret the cosmic symptoms just as hard as to {169} interpret those of our organism. In both instances the elements were complex and the chances of error infinite. All the examples of patients dying in spite of the physician, or on account of