Thoughts shut up want air, And spoil, like bales unopen'd to the sun.

Young likens unspoken thoughts to merchandise packed in bales: if kept closed and unexposed, they “spoil.” The metaphor suggests that ideas require circulation—expression, dialogue, and scrutiny—to stay vivid and useful. “Air” implies both literal openness (speaking or writing) and figurative illumination (the “sun” of reason, experience, or moral truth). The couplet also warns against solitary brooding: thoughts confined within the self can stagnate, distort, or decay. In Young’s broader moral vision, the line encourages candid communication and reflective disclosure as a means of intellectual and spiritual health, implying that the mind matures through exposure rather than secrecy.