From Athanasius' Life of Antony:
5. . . . But when the enemy [the devil] saw himself to be too weak for Antony's determination, and that he rather was conquered by the other's firmness, overthrown by his great faith and falling through his constant prayers, then at length putting his trust in the weapons which are 'in the navel of his belly' and boasting in them–for they are his first snare for the young–he attacked the young man, disturbing him by night and harassing him by day, so that even the onlookers saw the struggle which was going on between them. The one would suggest foul thoughts and the other counter them with prayers: the one fire him with lush the other, as one who seemed to blush, fortify his body with faith, prayers, and fasting. And the devil, unhappy wight, one night even took upon him the shape of a woman and imitated all her acts simply to beguile Antony.
But he, his mind filled with Christ and the nobility inspired by Him, and considering the spirituality of the soul, quenched the coal of the other's deceit. Again the enemy suggested the ease of pleasure. But he like a man filled with rage and grief turned his thoughts to the threatened fire and the gnawing worm, and setting these in array against his adversary, passed through the temptation unscathed. All this was a source of shame to his foe. For he, deeming himself like God, was now mocked by a young man; and he who boasted himself against flesh and blood was being put to flight by a man in the flesh. For the Lord was working with Antony–the Lord who for our sake took flesh and gave the body victory over the devil, so that all who truly fight can say, ' not I but the grace of God which was with me.'
6. At last when the dragon could not even thus overthrow Antony, but saw himself thrust out of his heart, gnashing his teeth as it is written, and as it were beside himself, he appeared to Antony like a black boy, taking a visible shape in accordance with the colour of his mind. And cringing to him, as it were, he plied him with thoughts no longer, for guileful as he was, he had been worsted, but at last spoke in human voice and said, 'Many I deceived, many I cast down; but now attacking thee and thy labours as I had many others, I proved weak.'
When Antony asked, Who art thou who speakest thus with me? he answered with a lamentable voice, 'I am the friend of whoredom, and have taken upon me incitements which lead to it against the young. I am called the spirit of lust. How many have I deceived who wished to live soberly, how many are the chaste whom by my incitements I have over-persuaded! I am he on account of whom also the prophet reproves those who have fallen, saying, "Ye have been caused to err by the spirit of whoredom." For by me they have been tripped up. I am he who have so often troubled thee and have so often been overthrown by thee.'
But Antony having given thanks to the Lord, with good courage said to him, ' Thou art very despicable then, for thou art black-hearted and weak as a child. Henceforth I shall have no trouble from thee, "for the Lord is my helper, and I shall look down on mine enemies."'
Having heard this, the black one straightway fled, shuddering at the words and dreading any longer even to come near the man.
7. This was Antony's first struggle against the devil, or rather this victory was the Saviour's work in Antony, 'Who condemned sin in the flesh that the ordinance of the law might be fulfilled in us who walk not after the flesh but after the spirit.' But neither did Antony, although the evil one had fallen, henceforth relax his care and despise him; nor did the enemy as though conquered cease to lay snares for him. For again he went round as a lion seeking some occasion against him.
But Antony having learned from the Scriptures that the devices of the devil are many, zealously continued the discipline, reckoning that though the devil had not been able to deceive his heart by bodily pleasure, he would endeavour to ensnare him by other means. . . .