From the Mystical City of God, Volume III, The Transfixion:
226... Immediately the prince of darkness, together with countless legions of evil spirits, issued forth from hell and spread over the whole world. They persisted in roaming through it many times, searching out in their malice and cunning all the just, tempting those they recognized as such and provoking them and other men to commit the evil deeds hatched out in their own infernal minds. But Christ our Lord in his wisdom concealed his own person and that of his Mother for many days from the haughty Lucifer. He did not permit him to see or recognize Him, until He betook Himself to the desert, where He allowed and wished the devil to tempt Him after his long fast; and Lucifer did tempt Him, as I shall relate in its place.
....285. Christ the Savior permitted Lucifer to remain under the false impression, that He was a mere human creature though very holy and just; He wished to raise his courage and malice for the contest, for such is the effect of any advantages espied by the devil in his attacks upon the victims of his temptations. Rousing his courage by his own arrogance, he began this battle in the wilderness with greater prowess and fierceness than the demons ever exhibited in their battles with men.