Thomas Aquinas

“ For every body is tangible that has qualities whereby the sense of touch has a natural aptitude to be affected: wherefore air, fire, and the like are tangible bodies: but a palpable body, in addition to this, resists the touch; wherefore the air which never resists that which passes through it, and is most easily pierced, is tangible indeed but not palpable. Accordingly it is clear that a body is said to be palpable for two reasons, namely on account of its tangible qualities, and on account of its resisting that which touches it, so as to hinder it from piercing it. ”

“ I answer that, A body is not related to place save through the medium of its proper dimensions, in respect of which a located body is confined through contact with the locating body. Hence it is not possible for a body to occupy a place smaller than its quantity, unless its proper quantity be made in some way less than itself: and this can only be understood in two ways. ”

“ And since incorporeal things lack quantity and matter, the term "subtlety" is applied to them, not only by reason of their substance, but also on account of their power. For just as a subtle thing is said to be penetrative, for the reason that it reaches to the inmost part of a thing, so is an intellect said to be subtle because it reaches to the insight of the intrinsic principles and the hidden natural properties of a thing. ”

“ It would seem that not even by a miracle is it possible for two bodies to be in the same place. For it is not possible that, by a miracle, two bodies be at once two and one, since this would imply that contradictions are true at the same time. ”

“ For three men differ not in genus, nor in species, but in their accidents. If we were to remove absolutely every accident from them, still each one has a different place; and it is quite conceivable that they should all occupy the same place." Therefore if we suppose two bodies to occupy the same place, there will be but one body numerically. ”

“ Hence in incorruptible, i.e. heavenly, bodies, there is only local movement, which is not according to something intrinsic. Thus it is clear that change of quantity in respect of matter would be incompatible with the impassibility and incorruptibility of a glorified body. Moreover, it would follow that a glorified body would be sometimes rarer and sometimes denser, because since it cannot be deprived of any of its matter, sometimes the same matter would be under great dimensions and sometimes under small dimensions, and thus it would be rarefied and densified, which is impossible. ”

“ Secondly, that the quantity of a glorified body become smaller than itself may be understood by a variation of place; so, to wit, that the parts of a glorified body insinuate themselves into one another, so that it is reduced in quantity however small it may become. ”

“ Secondly, through paucity of matter, wherefore rarity is synonymous with subtlety: and since in rare bodies the form is more predominant over the matter, the term "subtlety" has been transferred to those bodies which are most perfectly subject to their form, and are most fully perfected thereby: thus we speak of subtlety in the sun and moon and like bodies, just as gold and similar things may be called subtle, when they are most perfectly complete in their specific being and power. ”

“ The first subjection whereby the body is subject to the soul is to the effect of its participating in its specific being, in so far as it is subject to the soul as matter to form; and secondly it is subject to the soul in respect of the other operations of the soul, in so far as the soul is a principle of movement. ”

“ Further, subtlety is in bodies as a result of scarcity of matter, wherefore bodies that have less matter within equal dimensions are said to be more subtle; as fire in comparison with air, and air as compared with water, and water as compared with earth. ”

“ Because to be in several places at once is incompatible with the individual, by reason of its having being undivided in itself, for it would follow that it is divided as to place. on the other hand, to be in the same place with another body is incompatible with the individual as distinct from aught else. ”

“ Further, a thing cannot be done miraculously either against the common principles---for instance that the part be not less than the whole; since what is contrary to common principles implies a direct contradiction---or contrary to the conclusions of geometry which are infallible deductions from common principles---for instance that the three angles of a triangle should not be equal to two right angles. ”

“ Wherefore we observe that when two bodies merge into one, each loses its distinct being, and one indistinct being accrues to the two combined, as in the case of mixtures. Hence it is impossible for two bodies to remain two and yet be together unless each retain its distinct being which it had hitherto, in so much as each of them was a being undivided in itself and distinct from others. ”

“ For it supposes the existence, between two opposite superficies of a place, of a dimension proper to the place, with which dimension a dimension of the body put in occupation of the place would have to be identified: because it would then follow that the dimensions of two bodies occupying a place would become one dimension, if each of them were identified with the dimension of the place. ”

“ And since the tangible qualities are hot and cold and so forth, which are not found save in heavy and light bodies, which through being contrary to one another are therefore corruptible, it follows that the heavenly bodies, which by their nature are incorruptible, are sensible to the sight but not tangible, and therefore neither are they palpable. ”

“ And since the first cause can preserve a thing in being, though the second causes be done away, as appears from the first proposition of De Causis, therefore by God's power and by that alone it is possible for an accident to be without substance as in the Sacrament of the Altar. ”