Line 8's 'But patience to prevent / That murmur' introduces a personified voice that cuts off Milton's complaint. 'Prevent' here means 'come before, anticipate'—Patience interrupts the question before it becomes full-blown rebellion.
The answer rewrites the terms completely. God doesn't 'need' human work or gifts (lines 9-10). The real service is bearing 'his milde yoak'—a reference to Matthew 11:30, where Jesus calls his burden easy. The poem shifts from production (writing poems) to posture (patient acceptance).
Lines 12-14 give the final image: thousands of angels 'speed and post' on errands, but others 'only stand and waite' in God's throne room (Isaiah 6:2). Both are serving. The verb 'stand' is crucial—it's not passive resignation but active readiness, like a servant waiting for orders. Milton finds a way to value his enforced stillness.
The final line became one of English poetry's most quoted—partly because it consoles anyone sidelined by illness, age, or circumstance. But notice: Milton didn't actually take the advice. He spent the next two decades dictating epic poetry. The sonnet resolves his crisis theoretically, but his practice suggests he never fully accepted that standing and waiting was enough.