Rich the treasure,
Sweet the pleasure—
Sweet is pleasure after pain.

The lines compress a familiar moral-psychological idea into epigrammatic lyric form: pleasure is intensified by contrast with suffering. “Rich the treasure” suggests that what is gained after hardship feels more valuable, while “Sweet the pleasure” underscores the heightened savor of relief and reward. The final line states the principle explicitly—pain functions as a kind of dark backdrop that makes subsequent joy more vivid. In Dryden’s idiom, the couplet-like balance and repeated “sweet” also mimic the very sensation described: a lingering, reiterated taste. The sentiment fits Restoration-era tastes for pointed, musical reflections on love, loss, and recompense.