III
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The universe embraces all the objects that fall, or that can fall, under our cognisance. Of these some are its parts, the remaining ones must form its material. Nature, just like every manual art everywhere, requires material. Let me make this a little plainer. In ourselves the parts are hand, bones, sinews, eyes; the material is the sap of the digested food, which will be distributed for the nourishment of the parts. Again, blood is in a certain sense a part of us, but still it is material as well. For it goes to form other parts, and, none the less, it is among the parts that go to make up the whole body.