One of the greatest comets which ever struck the imagination of men was assuredly the famous comet of 1680, to which Newton devoted so much attention. “It issued,” said Lemonnier, “with a frightful velocity from the depths of space and seemed falling directly into the sun and was seen to vanish with an equal velocity. It was visible for four months. It approached quite near to the earth, and Whiston ascribed the deluge to its former appearance.” Bayle wrote a treatise to prove the absurdity of beliefs founded on these portents. Madame de Sévigné writing to her cousin, Count de Bussy-Rabutin, says: “We have a comet of enormous size; its tail is the most beautiful object conceivable. Every person of note is alarmed and believes that heaven, interested in their fate, sends them a warning in this comet. They say that the courtiers of Cardinal Mazarin, who is despaired of by his physicians believe this prodigy is in honor of his passing away, and tell him of the terror with which it has inspired them. He had the sense to laugh at them, and to reply facetiously that the comet did him too much honor. In truth we ought all to agree with him, for human pride assumes too much when it believes that death is attended by such signs from heaven.” We see that comets were gradually losing their prestige. Yet we read in a treatise of the astronomer Bernouilli this singular remark: “If the head of the comet be not a visible sign of the anger of God, _the tail may well be_.” Fear of the end of the world was reawakened by the appearance of comets in 1773; a great panic spread throughout Europe, and Paris itself was alarmed. Here is an extract from the memoirs of Bachaumont, accessible to every reader: “May 6th, 1773. In the last public meeting of the Academy of Sciences, M. de Lalande was to read by far the most interesting paper of all; this, however, he was not able to do, for lack of time. It concerned the comets which, by approaching the earth, may cause revolutions, and dealt especially with that one whose return is expected in eighteen years. But although he affirmed that it was not one of those which would harm the earth, and that, moreover, he had observed that one could not fix, with any exactness, the order of such occurrences, there exists, nevertheless, a very general anxiety. “May 9th. The cabinet of M. de Lalande is filled with the curious who come to question him concerning the above memoir, and, in order to reassure those who have been alarmed by the exaggerated rumors circulated about it, he will doubtless be forced to make it public. The excitement has been so great that some ignorant fanatics have besought the archbishop to institute prayers for forty hours, in order to avert the deluge which menaces us; and this prelate would have authorized these prayers, had not the Academy shown him the ridicule which such a step would produce.