232 PHYSICAL SCIENCE IN THE MIDDLE AGES. 



inament, from the waters under the firmament, he gives one opinion, 

 that of Bede, that the former waters are the solid crystalline heavens 

 in which the stars are fixed, 12 "for crystal, which is so hard and trans- 

 parent, is made of water." But he mentions also the opinion of St. 

 Augustine, that the waters above the heavens are in a state of vapor 

 (vaporaliter) and in minute drops; "if, then, water can, as we see u. 

 clouds, be so minutely divided that it may be thus supported as vapor 

 on air, which is naturally lighter than water ; why may we not believe 

 that it floats above that lighter celestial element in still minuter drops: 

 and still lighter vapors ? But in whatever manner the waters are 

 there, we do not doubt that they are there." 



The celebrated Summa Theologice of Thomas Aquinas is a work of 

 the same kind ; and any thing which has a physical bearing forms an 

 equally small part of it. Thus, of the 512 Questions of the Summa, 

 there is only one (Part. I., Quest. 115), "on Corporeal Action," or on 

 any part of the material world ; though there are several concerning 

 the celestial Hierarchies, as " on the Act of Angels," " on the Speaking 

 of Angels," " on the Subordination of Angels," " on Guardian Angels," 

 and the like. This, of course, would not be remarkable in a treatise 

 on Theology, except this Theology were intended to constitute the 

 whole of Philosophy. 



We may observe, that in this work, though Plato, Avecibron, and 

 many other heathen as well as Christian philosophers, are adduced as 

 authority, Aristotle is referred to in a peculiar manner as " the philos- 

 opher." This is noticed by John of Salisbury, as attracting attention 

 in his time (he died a.d. 1182). "The various Masters of Dialectic," 

 says he, 13 " shine each with his peculiar merit ; but all are proud to 

 worship the footsteps of Aristotle ; so much so, indeed, that the name 

 of philosopher, which belongs to them all, has been pre-eminently 

 appropriated to him. He is called the philosopher autonomatice, that 

 is, by excellence." 



The Question concerning Corporeal Action, in Aquinas, is divided 

 into six Articles ; and the conclusion delivered upon the first is, 14 that 

 " Body being compounded of power and act, is active as well as pas- 

 sive." Against this it is urged, that quantity is an attribute of body, 

 and that quantity prevents action ; that this appears in fact, since a 

 larger body is more difficult to move. The author replies, that "quan- 



12 Lib. ii. Distinct, xiv. Be opere secundce diei. 



13 Metalogieus, lib. ii. cap. 16. >* Sumrnce, P. i. Q. 115. Art. 1. 



