The poem is strange on purpose, and it doesn't hand over a clear story. It reads like a fragment of a dream or an odd piece of folk wisdom. It opens with a blunt, slightly absurd rule: an ape should be locked up "in case he should die." The logic doesn't quite hold, which is part of the point. It sounds like a warning from someone who is anxious and half-making sense.
Then the speaker turns to address parts of the body and a tool: "my brother Leg, / my brother Stick." Calling them brothers makes the speaker's own limbs and walking aid feel like a family, and the order "Do not sit down" suggests urgency, as if stopping might be dangerous. The title points the same way, treating laziness as a risk. The stick is both carried and feared, and called "the king" of all brethren. That mix of dependence and dread gives the poem its mood: tense, odd, a little comic, with something uneasy underneath. I'd read it as a speaker who must keep moving.