§ 50. Now, when he had attain'd thus far, so as to have a general and indistinct Motion of this _Agent_, he had a most earnest Desire to know him distinctly. And because he had not as yet withdrawn himself from the sensible World, he began to look for this _voluntary Agent_ among sensible Things; nor did he as yet know, whether it was one Agent or many. Therefore he enquir'd strictly into all such Bodies as he had about him, _viz_. those which he had been employ'd about all along, and he found that they were all liable to _Generation_ and _Corruption_: And if there were any which did not suffer a total Corruption, yet they were liable to a partial one, as _Water_ and _Earth_, the parts of which are consum'd by Fire. Likewise he perceiv'd, that the _Air_ was by extremity of Cold chang'd into Snow, and then again into Water; and among all the rest of the Bodies which he was conversant with, he could find none which had not its Existence anew, and required some _voluntary Agent_ to give it a Being. Upon which account he laid them all aside, and transferr'd his Thoughts to the Consideration of the Heavenly Bodies. And thus far he reach'd in his Contemplations, about the end of the fourth Septenary of his Age, _viz_. when he now eight and twenty Years old.
§ 51. Now he knew very well, that the Heavens, and all the Luminaries in them, were Bodies, because they were all extended according to the three Dimensions Length, Breadth and Thickness, without any exception; and that every thing that was so extended, was Body; _ergo_, they were all Bodies. Then, he consider'd next, whether they were extended infinitely, as to stretch themselves to an endless Length, Breadth and Thickness; or, whether they were circumscrib'd by any Limits, and terminated by some certain Bounds, beyond which there could be no Extension. But here he stopp'd a while, as in a kind of Amazement.
§ 52. At last, by the strength of his Apprehension, and Sagacity of his Understanding, he perceiv'd that the Notion of infinite Body was absurd and impossible, and a Notion wholly intelligible. He confirm'd himself in this Judgment of his, by a great many Arguments which occurr'd to him, when he thus argued with himself. _That this heavenly Body is terminated on this side which is next to me, is evident to my sight: And that it cannot be infinitely extended on that opposite side, which rais'd this Scruple in me; I prove thus: Suppose two Lines drawn from the Extremity of this Heavenly Body, on that terminated Side which is next to me, which Lines should be produc'd quite through this Body_, in infinitum, _according to the Extension of the Body; then suppose a long part of one of these Lines, cut off at this End which is next to me; then take the Remainder of what was cut off, and draw down that end of it where it was cut off; And lay it even with the end of the other Line from which there was nothing cut off; and let that Line which was shortned, lye parallel with the other; then suppose them through this Body, till you come to that side which we suppos'd to be infinite: Either you will find both these Lines infinitely extended, and then one of them cannot be shorter than the other, but that which had a part of it cut off, will be as long as that which was not, which is absurd: Or else the Line which was cut will not be so long as that other, and consequently finite: Therefore if you add that part to it which was cut off from it at first, which was finite, the whole will be finite; and then it will be no longer or shorter than that Line which had nothing cut off from it, therefore equal to it; But this is finite, therefore the other is finite. Therefore the Body in which such Lines are drawn is finite; And all Bodies in which such Lines may be drawn, are finite: But such Lines may be drawn in all Bodies. Therefore if we suppose an infinite Body, we suppose an Absurdity and Impossibility._
