in matter, matter moves figuratively. Yet do I not say, That there is no hindrance, obstruction and opposition in nature; but as there is no particular Creature, that hath an absolute power of self-moving; so that Creature which hath the advantage of strength, subtilty, or policy, shape, or figure, and the like, may oppose and over-power another which is inferior to it, in all this; yet this hinderance and opposition doth not take away self-motion. But I perceive your _Author_ is much for necessitation, and against free-will, which I leave to Moral Philosophers and Divines. And as for the ascending of light, and descending of heavy bodies, there may be many causes, but these four are perceiveable by our senses, as bulk, or quantity of body, grossness of substance, density, and shape or figure, which make heavy bodies descend: But little quantity, purity of substance, rarity, and figure or shape make light bodies ascend. Wherefore I cannot believe, that there are[3] _certain little bodies as atoms, and by reason of their smallness, invisible, differing from one another in consistence, figure, motion and magnitude, intermingled with the air_, which should be the cause of the descending of heavy bodies. And concerning air,[4] _whether it be subject to our senses or not_, I say, that if air be neither hot, nor cold, it is not subject; but if it be, the sensitive motions will soon pattern it out, and declare it. I'le conclude with your _Authors_ question,[5] _What the cause is, that a man doth not feel the weight of Water in Water?_ and answer, it is the dilating nature of Water. But of this question and of Water I shall treat more fully hereafter, and so I rest, Madam, _Your faithful Friend_ _and Servant._ [1] _C._ 30. _a._ 1. [2] _Art._ 2. [3] _Art._ 3. [4] _Art._ 14. [5] _Art._ 6. XXX. _MADAM,_