2 For many men are brave, when they are enduring persecution from men, and see them openly rage against themselves: imagining they are then imitating the sufferings of Christ, in case men openly persecute them; but if assailed by the hidden attack of the devil, they believe they are not being crowned by Christ. Never fear when thou dost imitate Christ. For when the devil tempted our Lord, there was no man in the wilderness; he tempted Him secretly; but he was conquered, and conquered too when openly attacking Him. This do thou, if you wish to enter by the door, when the enemy secretly assails you, when he asks for a man that he may do him some hurt by bodily troubles, by fever, by sickness, or any other bodily sufferings, like those of Job. He saw not the devil, yet he acknowledged the power of God. He knew that the devil had no power against him, unless from the Almighty Ruler of all things he received that power: the whole glory he gave to God, power to the devil he gave not....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)