use, benefit, and consistence of the body; for there is so much variety in this one act of digestion, as no man is able to conceive; and if there be such variety in one Particular natural action, what variety will there not be in all Nature? Wherefore, it is not, as I mentioned in the beginning, either Ferment, or Heat, or any other thing, that causes digestion; for if all the constitution and nature of our body was grounded or did depend upon Ferment, then Brewers and Bakers, and those that deal with Ferments, would be the best Physicians. But I would fain know the cause which makes Ferment? You may say, saltness, and sowreness. But then I ask, From whence comes saltness and sowreness? You may say, From the Ferment. But then I shall be as wise as before. The best way, perhaps, may be to say, with your _Author_, that Ferment is a Primitive Cause, and a beginning or Principle of other things, and it self proceeds from nothing. But then it is beyond my imagination, how that can be a Principle of material things, which it self is nothing; that is, neither a substance, nor an accident. Good Lord! what a stir do men make about nothing! I am amazed to see their strange Fancies and Conceptions vented for the Truest Reasons: Wherefore I will return to my simple opinion; and as I cannot conceive any thing that is beyond Matter, or a Body; so I believe, according to my reason, that there is not any part in Nature, be it never so subtil or small, but is a self-moving substance, or endued with self-motion; and according to the regularity and irregularity of these motions, all natural effects are produced, either perfect, or imperfect; timely births, or untimely and monstrous births; death, health, and diseases, good and ill dispositions, natural and extravagant Appetites and Passions, (I say natural, that is, according to the nature of their figures;) Sympathy and Antipathy, Peace and War, Rational and Phantastical opinions. Nevertheless, all these motions, whether regular or irregular, are natural; for regularity and irregularity hath but a respect to particulars, and to our conceptions, because those motions which move not after the ordinary, common or usual way or manner, we call Irregular. But the curiosity and variety in Nature is unconceiveable by any particular Creature; and so leaving it, I rest, Madam, _Your faithful Friend_ _and Servant._ XXX. _MADAM,_