Among his other practical services to rationalism was a curious experiment, made in a village of the Lower Alps, by way of investigating the doctrine of witchcraft. A drug prepared by one sorcerer was administered to others of the craft in presence of witnesses. It threw them into a deep sleep, on awakening from which they declared that they had been at a witches' Sabbath. As they had never left their beds, the experiment went far to discredit the superstition. [305] One significant result of the experiment was seen in the course later taken by Colbert in overriding a decision of the Parlement of Rouen as to witchcraft (1670). That Parlement proposed to burn fourteen sorcerers. Colbert, who had doubtless read Montaigne as well as Gassendi, gave Montaigne's prescription that the culprits should be dosed with hellebore--a medicine for brain disturbance. [306] In 1672, finally, the king issued a declaration forbidding the tribunals to admit charges of mere sorcery; [307] and any future condemnations were on the score of blasphemy and poisoning. Yet further, in the section of his posthumous Syntagma Philosophicum (1658) entitled De Effectibus Siderum, [308] Gassendi dealt the first great blow on the rationalist side to the venerable creed of astrology, assailed often, but to little purpose, from the side of faith; bringing to his task, indeed, more asperity than he is commonly credited with, but also a stringent scientific and logical method, lacking in the polemic of the churchmen, who had attacked astrology mainly because it ignored revelation. It is sobering to remember, however, that he was one of those who could not assimilate Harvey's discovery of the circulation of the blood, which Descartes at once adopted and propounded. Such anomalies meet us many times in the history of scientific as of other lines of thought; and the residual lesson is the recognition that progress is infinitely multiplex in its causation. Nothing is more vital in this regard than scientific truth, which is as a light-house in seas of speculation; and those who, like Galileo and Descartes, add to the world's exact knowledge, perform a specific service not matched by that of the Bacons, who urge right method without applying it. Yet in that kind also an incalculable influence has been wielded. Many minds can accept scientific truths without being thereby led to scientific ways of thought; and thus the reasoners and speculators, the Brunos and the Vaninis, play their fruitful part, as do the mentors who turn men's eyes on their own vices of intellectual habit. And in respect of creeds and philosophies, finally, it is not so much sheer soundness of result as educativeness of method, effectual appeal to the thinking faculty and to the spirit of reason, that determines a thinker's influence. This kind of impact we shall find historically to be the service done by Descartes to European thought for a hundred years.