Angels are said to be in place equivocally as compared with bodies; for a body is in a place according to the contact of dimensional quantity, but an angel by the application of power. Hence an angel is not measured by place, nor has it a particular position.
Incorporeal substance, indeed, is said to contain rather than to be contained; thus the soul is in the body as containing, not as contained. By the application of power, however, to any place, the angel may be said to be in some manner in that material place, though not contained in place. For an angel is not everywhere, but in one particular place, its power being finite; while God is everywhere because His power is infinite; and the universe, compared with His universal power, is as one single thing. After divers modes, therefore, it pertains to bodies, to angels and to God to be in place. For a body is measured by place and therefore circumscribed by it; an angel is present not as circumscribed but as limited, i.e. being so in one place that it cannot be also in another; and God as neither circumscribed nor limited, because He is everywhere.
Nor are two angels in one place at the same time, for there cannot be at once two total and immediate causes for the same effect. And this notwithstanding the example adduced of several forces united in drawing a boat; for these do not constitute singly a perfect motor, but several, singly insufficient, unite their powers to produce one motor, while the angel is in a place as containing it perfectly.
- text taken from Compendium of the Summa Theologica of Saint Thomas Aquinas, by Bishop Berardus Bongiovanni