If I when my wife is sleeping
and the baby and Kathleen
are sleeping
As is typical of many of Williams's poems, this one begins with concrete scene-setting. The speaker's wife, baby, and a woman named Kathleen—who we can infer is a relative or a nanny—are also asleep, immediately implying that this is occurring in the early morning. The use of "if," however, is very notable, as it immediately sets up the scene as a conditional moment, framing the events that follow as hinging on this specific set of circumstances. This is important in that it shows the necessary condition of the speaker being alone for him to feel comfortable dancing.
“I am lonely, lonely.
I was born to be lonely,
I am best so!”
The sincerity of these lines is somewhat questionable as the speaker is singing them to himself as he dances. However, they do underscore the importance of his solitary state at this particular moment. By repeating the word "lonely" so many times before declaring that he is "best so," the speaker is showing the joy that he feels in his aloneness. While the wording of this quote is purposefully comical, the sentiment it outlines comes across as genuine. He only gets this chance to reflect and observe because he is by himself.
If I admire my arms, my face,
my shoulders, flanks, buttocks
against the yellow drawn shades,—
Here, the "if" makes its third appearance in the poem. This is, in many ways, the most pivotal scene in the poem. The speaker "admires" himself in the mirror, cataloging the various parts of his body. This is the high point of his reflection on himself and his appearance. After naming the circumstances under which this dancing before the mirror occurs, he has come to the moment in which he is actually looking at himself most closely. The dash that ends this section gives the section a certain urgency, as if the speaker has made this catalog as part of an outburst.