And I have known the arms already, known them all— Arms that are braceleted and white and bare (But in the lamplight, downed with light brown hair!) Is it perfume from a dress That makes me so digress? Arms that lie along a table, or wrap about a shawl. And should I then presume? And how should I begin?
To summarize this part, he seems to start by saying that he's known so many women that they've become the same or very similar to him. He then says that their perfume makes him digress or deviate from the subject as it makes him forget this problem. It keeps him from making his statement until he doesn't know how to continue or start.