After she had spoken these words, the heavens were shut. I was overwhelmed with sorrow and fear, and said to myself, “If this sin is assigned to me, how can I be saved, or how shall I propitiate God in regard to my sins, which are of the grossest character? With what words shall I ask the Lord to be merciful to me?” While I was thinking over these things, and discussing them in my mind, I saw opposite to me a chair, white, made of white wool, of great size. And there came up an old woman, arrayed in a splendid robe, and with a book in her hand; and she sat down alone, and saluted me, “Hail, Hermas!”
And in sadness and tears I said to her, “Lady, hail!” And she said to me, “Why are you downcast, Hermas? For you were wont to be patient and temperate, and always smiling. Why are you so gloomy, and not cheerful?” I answered her and said, “O Lady, I have been reproached by a very good woman, who says that I sinned against her.” And she said, “Far be such a deed from a servant of God. But perhaps a desire after her has arisen within your heart. Such a wish, in the case of the servants of God, produces sin. For it is a wicked and horrible wish in an all-chaste and already well-tried spirit to desire an evil deed; and especially for Hermas so to do, who keeps himself from all wicked desire, and is full of all simplicity, and of great guilelessness.”
Source: The Pastor (or "The Shepherd") (New Advent)