But I pray, _Madam_, consider rationally, that though the Artificer or Workman be the occasion of the motions of the carved body, yet the motions of the body that is carved, are they which put themselves into such or such a figure, or give themselves such or such a print as the Artificer intended; for a Watch, although the Artist or Watch-maker be the occasional cause that the Watch moves in such or such an artificial figure, as the figure of a Watch, yet it is the Watches own motion by which it moves; for when you carry the Watch about you, certainly the Watch-makers hand is not then with it as to move it; or if the motion of the Watch-makers hand be transferred into the Watch, then certainly the Watch-maker cannot make another Watch, unless there be a new creation of new motions made in his hands; so that God and Nature would be as much troubled and concerned in the making of Watches, as in the making of a new World; for God created this World in six days, and rested the seventh day, but this would be a perpetual Creation; Wherefore I say that some things may be Occasional causes of other things, but not the Prime or Principal causes; and this distinction is very well to be considered, for there are no frequenter mistakes then to confound these two different causes, which make so many confusions in natural Philosophy; and this is the Opinion of, Madam, _Your Faithful Friend_ _and Servant._ XXIV. _MADAM,_ In answer to your question, What makes Eccho, I say, it is that which makes all the effects of Nature, _viz._ self-moving matter; I know, the common opinion is, that Eccho is made like as the figure of a Face, or the like, in a Looking-glass, and that the Reverberation of sound is like the Reflection of sight in a Looking-glass; But I am not of that opinion, for both Eccho, and that which is called the Reflection in a Looking-glass, are made by the self-moving matter, by way of patterning and copying out. But then you will ask me, whether the glass takes the copy of the face, or the face prints its copy on the glass, or whether it be the _medium_ of light and air that makes it? I answer, although many Learned men say, that as all perception, so also the seeing of ones face in a Looking-glass, and Eccho, are made by impression and reaction; yet I cannot in my simplicity conceive it, how bodies that come not near, or touch each other, can make a figure by impression and reaction: They say it proceeds from the motions of the _Medium_ of light, or air, or both, _viz._ that the _Medium_ is like a long stick with two ends, whereof one touches the object, the other the organ of sense, and that one end of it moving, the other moves also at the same point of Time, by which motions it may make many several figures; But I cannot conceive, how this motion of pressing forward and backward should make so many figures, wherein there is so much variety and curiosity. But, say light and air are as one figure, and like as a