The editor of the NAEL hails this poem as a “superb satire”, but in my opinion, when it takes miles of footnotes to understand the satire (unless you are a seventeenth-century scholar), it rather deflates it, like all explaining of a joke. “Mac Flecknoe” is a satire directed against a poet Thomas Shadwell, whom Dryden considered a lousy poet, perhaps justifiably. In order to do this, he picked another lousy poet Richard Flecknoe (who happened to be a Catholic priest), then recently deceased, and portrayed him as looking for a poetic heir in dullness and lack of imagination. Hence “Mac” of the title – as in “the son of” in Scottish and Irish. As a side note, when Dryden was stripped of his Poet Laureateship, it was Shadwell who got it. It must have hurt.
The poem begins with Flecknoe, “this aged prince”, looking for a successor. (Since the succession after Charles II was such a hot topic back then, I wonder if it is an undercurrent here.) Flecknoe does not look for long and immediately decides that Shadwell, masked here as Sh——, is his heir in stupidity. Omitting names was a convention in the satire of this era, but maybe it could be also a nasty joke, reminding the readers here about another word starting with “sh”, especially since later in the poem we have an image of Shadwell’s boat followed by little fishes like they follow “the morning toast that floats along” (“toast” meaning “sewage”). Other poets may have a moments of lucidity, but Shadwell is boring through and through. Even Flecknoe has to admit he was just sent to foretell the arrival of a bigger dunce than him, like John the Baptist was sent before Jesus. There are some jokes referring to Shadwell’s play, to elaborate to analyse here, and to the monotonousness of his verse. Here Flecknoe stops and weeps for joy.