_B._ And I think Copernicus himself would have said the same, if his purpose had been to have shown the natural causes of the motions of the stars. But that was no part of his design; which was only from his own observations, and those of former astronomers, to compute the times of their motions; partly to foretel the conjunctions, oppositions, and other aspects of the planets; and partly to regulate the times of the Church’s festivals. But his followers, Kepler and Galileo, make the earth’s motion to be the efficient cause of the monthly motion of the moon about the earth; which without the like motion to that of the sun in L M, is impossible. Let us therefore for the present take it in as a necessary hypothesis; which from some experiment that I shall produce in our following discourses, may prove to be a certain truth. _A._ But seeing A is the centre both of the sun’s body and of the annual motion of the earth, how can it be (as all astronomers say it is) that the orb of the annual motion of the earth should be eccentric to the sun’s body? For you know that from the vernal equinox to the autumnal, there be one hundred and eighty-seven days; but from the autumnal equinox to the vernal, there be but one hundred and seventy-eight days. What natural cause can you assign for this eccentricity? _B._ Kepler ascribes it to a magnetic virtue, viz. that one part of the earth’s superficies has a greater kindness for the sun than the other part. _A._ I am not satisfied with that. It is magical rather than natural, and unworthy of Kepler. Tell me your own opinion of it. _B._ I think that the magnetical virtue he speaks of, consisteth in this: that the southern hemisphere of the earth is for the greatest part sea, and that the greatest part of the northern hemisphere is dry land. But how it is possible that from thence should proceed the eccentricity (the sun being nearest to the earth, when he is in the winter solstice), I shall show you when we come to speak of the motions of air and water. _A._ That is time enough: for I intend it for our next meeting. In the mean time I pray you tell me what you think to be the cause why the equinoctial, and consequently the solstitial, points are not always in one and the same point of the ecliptic of the fixed stars. I know they are not, because the sun does not rise and set in points diametrically opposite: for if it did, there would be no difference of the seasons of the year.