greater and lesser. Now you see that the cause of the Monethly Period resideth in the annual motion; and withal you see how much the Moon is concerned in this business, and how it is therewith interrupted apart, without having any thing to do with either, with Seas or Waters.
Sagr.If one that never had seen any kinde of Stairs or Lader, were shewed a very high Tower, and asked if ever he hoped to climb to the top of it, I verily believe that he would answer he did not, not conceiving how one should come thither any way except by flying; but shewing him a stone of but a foot high, and asking him whether he thought he could get to the top of that, I am certain that he would answer he could; and farther, that he would not deny, but that it was not onely one, but ten, twenty, and an hundred times easier to climb that: But now if he should be shewed the Stairs, by means whereof, with the facility by him granted, it is possible to get thither, whither he a little before had affirmed it was impossible to ascend, I do think that laughing at himself he would confess his dulness of apprehension. Thus, Salviatus, have you step by step so gently lead me, that, not without wonder, I finde that I am got with small pains to that height which I despaired of arriving at. 'Tis true; that the Staircase having been dark, I did not perceive that I was got nearer to, or arrived at the top, till that coming into the open Air I discovered a great Sea, and spacious Country: And as in ascending one step, there is no labour; so each of your propositions by it self seemed to me so plain, that thinking I heard but little or nothing that was new unto me, I conceived that my benefit thereby had been little or none at all: Whereupon I was the more amazed at the unexpected exit of this discourse, that hath guided me to the knowledge of a thing which I held impossible to be demonstrated. One doubt onely remains, from which I desire to be freed, and this it is; Whether that if the motion of the Earth together with that of the Moon under the Zodiack are irregular motions, those irregularities ought to have been observed and taken notice of by Astronomers, which I do not know that they are: Therefore I pray you, who are better acquainted with these things than I, to free me from this doubt, and tell me how the case stands.
Salv.You ask a rational question, and answering to the Objection, Many things may remain as yet unobserved in Astronomy.I say; That although Astronomy in the courses of many ages hath made a great progress in discovering the constitution and motions of the Celestial bodies, yet is it not hitherto arrived at that height, but that very many things remain undecided, and haply many others also undiscovered. It is to be supposed that the first observers of Heaven knew no more but one motion commonto
