Mr. Lecky ought to have written "may be;" but the meaning of the words would have been very different, and their point would have been taken away. Secondly, while St. Thomas teaches, in accordance with Holy Writ, that the demons can exercise power over material things, he also teaches that they cannot directly change the qualities of things, nor produce any preternatural change except local motion: nor that at their pleasure; for it is a principle with him that God does not permit them to do all that which they have _per se_ the power of doing. [Footnote 21] [Footnote 21: Questiones de Malo, q. 16, art. 9, etc.; Questiones de Potentia Dei, q 6. art. 5.] Thirdly, as to their natural power of transmuting our bodies. We have not been able to find the exact words quoted above, but many similar phrases occur in the _objections_ in the ninth article of the _Quaestio de Daemonibus_, which, it is sufficient to say, St. Thomas solves by saying: But on the other hand, St. Augustine [Footnote 22] says "Non solum animam sed nec corpus quidem nulla ratione crediderim daemonom arte vel potestate in brutalia lineamenta poese converti." ... I reply that, as the apostle says, "all things made by God in order," whence, as St. Augustine says, "the excellence of the universe is the excellence of order. ... and therefore Satan always uses natural agents as his instruments in the production of physical effects, and can so produce effects which exceed the efficacy of the natural agents; [Footnote 23] but he cannot cause the form of the human body to be changed into that of an animal, because this would be contrary to the order established by God; and all such conversions are, therefore, as Augustine shows in the place quoted, according to phantastical appearance rather than truth. [Footnote 22: De Civ. Dei. 1. 18, c. 88.] [Footnote 23: I.e., which exceeds their ordinary effects, because he can use them more skillfully (cf. ad. 11).]