Whether observances directed to the alteration of bodies, as for the purpose of acquiring health or the like, are unlawful?

Objections

Objection 1 : It would seem that observances directed to the alteration of bodies, as for the purpose of acquiring health, or the like, are lawful. It is lawful to make use of the natural forces of bodies in order to produce their proper effects. Now in the physical order things have certain occult forces, the reason of which man is unable to assign; for instance that the magnet attracts iron, and many like instances, all of which Augustine enumerates (De Civ. Dei xxi, 5,7). Therefore it would seem lawful to employ such like forces for the alteration of bodies.
Objection 2 : Further, artificial bodies are subject to the heavenly bodies, just as natural bodies are. Now natural bodies acquire certain occult forces resulting from their species through the influence of the heavenly bodies. Therefore artificial bodies, e.g. images, also acquire from the heavenly bodies a certain occult force for the production of certain effects. Therefore it is not unlawful to make use of them and of such like things.
Objection 3 : Further, the demons too are able to alter bodies in many ways, as Augustine states (De Trin. iii, 8,9). But their power is from God. Therefore it is lawful to make use of their power for the purpose of producing these alterations.