Checking a few dictionaries for the word discursive, one may find such definitions as rambling, covering a wide range of subjects, or moving from topic to topic without order. But most dictionaries also include a secondary definition, noting that discursive talk or thought is marked by analytical reasoning, or proceeding to a conclusion through reason. Both these meanings apply to Pinsky's "Song of Reasons." A more common style, the lyric, also pertains to this poem, although it may not be apparent until over halfway through. Simply put, a lyric expresses subjective thoughts and feelings, which Pinsky works his way into at line 15, when the topic suddenly switches to his daughter.

Obviously, "Song of Reasons" covers a wide range of topics—from Italian music, French history, and Judaism, to TV stars, a child reading the newspaper, and a city street. Knowing only that, one could assume the...