Whether men are assailed by the demons?

Objections

Objection 1 : It would seem that men are not assailed by the demons. For angels are sent by God to guard man. But demons are not sent by God: for the demons' intention is the loss of souls; whereas God's is the salvation of souls. Therefore demons are not deputed to assail man.
Objection 2 : Further, it is not a fair fight, for the weak to be set against the strong, and the ignorant against the astute. But men are weak and ignorant, whereas the demons are strong and astute. It is not therefore to be permitted by God, the author of all justice, that men should be assailed by demons.
Objection 3 : Further, the assaults of the flesh and the world are enough for man's exercise. But God permits His elect to be assailed that they may be exercised. Therefore there is no need for them to be assailed by the demons.