this motion is due to more than place alone), (2) rubbing the
loadstone with garlic acts as if it impedes or alters the "virtus
magnetis," and (3) the iron must be properly aligned with respect to
the loadstone in order to be moved, especially if the loadstone is
small. Thus the iron is moved by the magnet not only to a place, but
also by changing and altering it: one has not only the change of
locomotion but that of alteration. Moreover the source of this
alteration in the iron is not the heavens but the loadstone.
Accordingly the loadstone could cause change in another substance
because it could influence the nature of the other substance.

[22] St. Thomas Aquinas, _op. cit._ (footnote 19), vol 7,
_Scriptum in quartum librum sententiarum magistri Petri
Lombardi_, lib. 4, disq. 33 (De diversis coniugii legibus),
art. 1 (Utrum habere plures uxores sit contra legem naturae),
p. 168. The same statement occurs in one of his most mature
works, _op. cit._ vol. 20, _Summa theologica_, pars 3
(supplementum), quaestio 65 (De pluralitate uxorum in quinque
articulos divisa), art. 1 (Utrum habere plures uxores sit
contra legem naturae), p. 107.

[23] St. Thomas Aquinas, _op. cit._ (footnote 19), vol. 8,
_Quaestio unica: de spiritualibus creaturis_, art. 2 (Utrum
substantia spiritualis possit uniri corpori), p. 404. See
also vol. 9, _Summa contra gentiles_, lib. 3, cap. 92
(Quomodo dicitur aliquis bene fortunatus, et quomodo
adjuvatur homo ex superioribus causis), p. 344; and vol. 17,
_Opuscula, De operationibus occultis naturae ad queindam
militem ultramontem_, pp. 213-214.

[24] St. Thomas Aquinas, _op. cit._ (footnote 19), vol. 8,
_Quaestio unica: de anima_, art. 1 (Utrum anima humana possit
esse forma et hoc aliquid), p. 437. See also vol. 8,
_Quaestio: De veritate_, quaestio 5 (De providentia), art. 10
(Utrum humani actus a divina providentia gubernentur mediis
corporibus coelestibus), p. 678.

[25] St. Thomas Aquinas, _op. cit._ (footnote 19), vol. 2,
_Physicorum Aristotelis expositio_, lib. 7, lect. 3, cap. g
(Probatur in motu locali quod movens et motum oportet esse
simul), p. 97 (quoted in Gilbert, M: p. 104).

About the time that St. Thomas was writing his letter _De
operationibus occultis naturae_ to a certain knight, Petrus Peregrinus
was writing from a military camp a letter in which he showed how
certai