aliæ tenuiores, quamvis totum corpus ex ipsis compositum tenue dici posset. 52. I reply: As regards their figure, we neither can nor should be affirmative, since it escapes our senses, being too delicate for our sight or our touch. That we must leave to themselves, and to such as have the privilege of intuitive acquaintance with immaterial substances. But, so far as probability goes, I say that their figure tallies with the human body, save some distinctive peculiarity, should the very tenuity of their body not be deemed sufficient. I am led to that by the consideration that of all the works of God the human frame is the most perfect, and that whilst all other animals stoop to the ground, because their soul is mortal, God, as Ovid, the poet, says, in his _Metamorphoses_, _Gave man an erect figure, bidding him behold the heavens And raise his face towards the stars_, man’s soul having been made immortal for the heavenly abode. Considering that the animals we are speaking of would be gifted with a spirit immaterial, rational and immortal, capable therefore of beatitude and damnation, it is proper to admit that the body to which that spirit is united may be like unto the most noble animal frame, that is to say to the human frame. Whence it follows that in the divers parts of that body there must be an essential order; that the foot, for instance, cannot be an appendage to the head, nor the hand to the belly, but that each organ is in its right place, according to the functions it has to perform. As to the constitutive parts of those organs, it is, in my opinion, necessary that there should be some more or less strong, others more or less slender, in order to meet the requirements of the organic working. Nor can this be fairly objected to on the ground of the slenderness of the bodies themselves; for the strength or thickness of the organic parts alluded to would not be absolute, but merely in comparison with the more slender ones. That, moreover, may be observed in all natural fluids, such as wine, oil, milk, etc.; however homogeneous and similar to each other their component parts may look, yet they are not so: for some are clayish, others aqueous; there are fixed salts, volatile salts, brimstone, all of which are made obvious by a chemical analysis. So it would be in our case: for, supposing the bodies of those animals to be as subtile and slender as the natural fluids, air, water, etc., there would nevertheless be discrepancies in the quality of their constitutive parts, some of which would be strong when compared with others more slender, although the whole body which they compose might be called slender.