The difficulty is much greater, if we suppose that these spirits are absolutely disengaged from any kind of matter; for how can they assemble about them a certain quantity of matter, clothe themselves with it, give it a human form, which can be discerned; is capable of acting, speaking, conversing, eating and drinking, as did the angels who appeared to Abraham,[441] and the one who appeared to the young Tobias,[442] and conducted him to Rages! Is all that accomplished by the natural power of these spirits? Has God bestowed on them this power in creating them, and has he engaged himself by virtue of his natural laws, and by a consequence of his acting intimately and essentially on the creature, in his quality of Creator, to impress on occasion at the will of these spirits certain motions in the air, and in the bodies which they would move, condense, and cause to act, in the same manner proportionally that he has willed by virtue of the union of the soul with a living body, that that soul should impress on that body motions proportioned to its own will, although, naturally, there is no natural proportion between matter and spirit, and, according to the laws of physics, the one cannot act upon the other, unless the first cause, the Creator, has chosen to subject himself to create this movement, and to produce these effects at the will of man, movements which without that would pass for superhuman (supernatural). Or shall we say, with some new philosophers,[443] that although we may have ideas of matter and thought, perhaps we shall never be capable of knowing whether a being purely material thinks or not, because it is impossible for us to discover by the contemplative powers of our own minds without revelation, if God has not given to some collections of matter, disposed as he thinks proper, the power to perceive and to think, or whether he has joined and united to the matter thus arranged, an immaterial substance which thinks? Now in relation to our notions, it is not less easy for us to conceive that God can add to our idea of matter the faculty of thinking, since we know not in what thought consists, and to what species of substance that Almighty being has judged proper to grant this faculty, which could exist in no created being except by virtue of the goodness and the will of the Creator.