duced by the form operating through the
active qualities of one substance, on the relatively passive qualities
of another. St. Thomas asserted the loadstone to be one of these
minerals, the occult powers of whose form goes beyond those of the
prime qualities.[23]

Forma enim elementi non habet aliquam operationem nisi quae
fit per qualitates activas et passivas, quae sunt
dispositiones materiae corporalis. Forma autem corporis
mineralis habet aliquam operationem excedentem qualitates
activas et passivas, quae consequitur speciem ex influentia
corporis coelestis, ut quod magnes attrahit ferrum, et quod
saphirus curat apostema.

That this occult power of the loadstone is a result of the direct
influence of the "virtus coeli" was expounded at greater length in
his treatise on the soul.[24]

Quod quidem ex propriis formarum operationibus perpendi
potest. Formae enim elementorum, quae sint infimae et
materiae propinquissime, non habent aliquam operationem
excedentem qualitates activas et passivas, ut rarum et
densum, et aliae huiusmodi, qui videntur esse materiae
dispositiones. Super has autem sunt formae mistorum quae
praeter praedictas operationes, habent aliquam operationem
consequentem speciem, quam fortiuntur ex corporibus
coelestibus; sicut quod magnes attrahit ferrum non propter
calorem aut frigiis, aut aliquid huiusmodi; sed ex quadam
participatione virtutis coelestis. Super has autem formas
sint iterum animae plantarum, quae habent similitudinem non
solum ad ipsa corpora coelestia, sed ad motores corporum
coelestium, inquantum sunt principia cuiusdam motus,
quibusdam seipsa moventibus. Super has autem ulterius sunt
animae brutorum, quae similitudinem iam habent ad substantiam
moventem coelestia corpora, non solum in operatione qua
movent corpora, sed etiam in hoc quod in seipsis
cognoscitivae sunt, licet brutorum cognitio sit materialium
tantum et materialiter....

St. Thomas placed the form of the magnet and its powers in the
hierarchy of forms intermediate between the forms of the inanimate
world and the forms of the organic world with its hierarchy of plant,
animal and rational souls. The form of the loadstone is then superior
to that of iron, which can only act through its active and passive
qualities, but inferior to the plant soul, that has the powers of
growth from the "virtus coeli." This is si