It also includes a memorable anecdote titled, "How the Devil Upset the Lamp Without Spilling It, During His Sermon":
...One day, after preaching and other deeds of charity, [St. Dominic] came when it was late to the sisters.... As they were sitting together behind the grille, and his brethren were likewise seated beside him, he began to preach to them once more about the wiles of the enemy, showing how Satan, for the sake of deceiving souls, transforms himself not merely into an angel of light, but assumes the shapes of the vilest creatures to hinder preaching and other good works, sometimes even taking the shape of a common sparrow.
The venerable father had scarcely said the word ere the enemy of mankind came on the scene in the shape of a sparrow, and began to fly through the air, and hopping even on the sisters' heads, so that they could have handled him had they been so minded, and all this to hinder the preaching.
St Dominic observing this, called Sister Maximilla, and said: 'Get up and catch him, and fetch him here to me.'
She got up and, putting out her hand, had no difficulty in seizing hold of him, and handed him out through the window to St Dominic. St Dominic held him fast in one hand and commenced plucking off the feathers with the other, saying the while: 'You wretch, you rogue!'
When he had plucked him clean of all his feathers amid much laughter from the brothers and sisters, and awful shrieks of the sparrow, he pitched him out, saying: 'Fly now if you can, enemy of mankind! You can cry out and trouble us, but you can't hurt us!'
The sparrow hopped once more through the window into the church, while all the sisters sat down to hear the sermon, then climbing up to the brass vessel, suspended by chains, which held the oil lamp, he broke the chains with a strong wrench and overturned the vessel. The lamp fell out, but not only was it not damaged or extinguished, but went on burning upside down. The sisters all looked up at the crash of the upset, and saw the lamp standing without any support in mid-air....
The sparrow which flew in that night disappeared, and no one saw whither he went.... Dominic wrought this laughter-stirring miracle by the window in St Sixtus' church, in the presence of Sister Cecilia, who saw and heard all that had been said, and of the other sisters of St Sixtus who were also present.
And the question is: Now that we know this story, what are we supposed to do with it?
One tack is to naturalize the story, perhaps along these lines: Once, when St. Dominic was talking about the devil with the nuns, a sparrow flew into room and acted the way somewhat tame sparrows act when inside rooms. Mistaking the sparrow for the devil -- a real possibility in medieval times -- St. Dominic grabbed it and pulled its feathers off. Then -- maybe that night, maybe that visit, maybe some other time -- an oil lamp in the church fell off its chain, but didn't cause a fire or even much of a mess, and this was attributed to him as a miracle.
Another tack is to psychoanalyze the story: The devil appears in the midst of a group of religious (albeit under a benign enough appearance, and whatever the actual nature of the bird what matters is what those present thought it was). Their reaction? "Much laughter" while their founder plucks it clean of feathers amid its "awful shrieks." Surely there's some sort of group pathology at work when people laugh at [what they believe is] the devil instead of fearing it. (And the less said of St. Dominic's manic, impromptu turn as the Clown to the devil's Policeman, the better.)
For my part, though, I'm inclined to take the tack of accepting the story on its own terms. Not to look for evidence of the "historical Dominic" by way of a sort of higher criticism, not to read it as a case study of medieval behavior, but to take it as a story told by an elderly nun about a real live saint she knew personally.
On those terms, the story is a parable of the foolishness of devils and the wisdom of saints. Those who see by the light of Christ can see through the deceptions of the enemy, and when seen through and exposed the deceptions are, literally, ridiculous.