Mercury goes regularly round the Sun in nearly a circular orbit, of which that luminary is the central point. Next to Mercury is Venus, which turns in the same manner round the Sun. Afterwards comes the Earth, and being higher than Mercury and Venus, describes a larger circle round the Sun than either of those planets. Then follow Mars, Jupiter and Saturn, in the order I have named them; thus you see the circle of Saturn must be the most extensive of all; it likewise requires a longer time than the other planets to perform its revolution. But, exclaimed she, you have forgotten the moon. I shall recollect it presently, said I; the moon never abandons the earth, but is constantly going round it; but as the earth is continually moving onwards in a circle round the sun, the moon at once follows its motion, and revolves round it; this attendant planet, therefore only goes round the sun in consequence of invariably continuing near to the earth. [Footnote 9: He was born in 1472, at Thorn, in Prussia Royal: he died in 1543.] [Footnote 10: Several of the ancients were of opinion that we should admit the motion of the earth. Astron. Art. 1075.] I understand you, said she, and I love the moon for remaining attached to us when we were forsaken by all the other planets. Confess that if your German could have alienated that too, he would have done it without regret; for one may see, in every part of his hypothesis, that he was but little inclined to favour the earth. He did well, I replied, to humble the vanity of men who chuse to claim the best situation in the universe; 'tis with pleasure I consider the world mixing in the crowd of planets. Pshaw! cried the Marchioness; do you think vanity can have any thing to do with a system of astronomy? Do you suppose I feel humbler for knowing that the earth goes round the sun? I assure you I esteem myself just as highly as I did before. Certainly, madam, I answered, men would be less concerned about the rank they held in the universe than that they enjoyed amongst their associates; neither would the disputes of two planets, for precedence, be so important in their judgement as those of two ambassadors. Nevertheless, the same disposition which induces a man of the world to aspire after the most honourable place in a room, will make a philosopher desirous of placing the globe on which he lives in the most distinguished situation in the universe. He likes to consider every thing made for his use; he encourages, without being aware of his vanity, so flattering an opinion, and his heart becomes deeply engaged about an affair of mere speculation. Upon my word, she exclaimed, you are calumniating human nature--how happened it that the opinions of Copernicus were received, since they are so very humiliating? Copernicus, answered I, was himself very doubtful of the reception they would meet with: it was a long while before he could resolve to publish his system; at