The birds are molting. If only man could molt also — his mind once a year its errors, his heart once a year its useless passions.

Using the natural image of birds shedding old feathers, Allen imagines a comparable human capacity for periodic renewal. “Molting” becomes a metaphor for deliberate self-purification: the mind discarding mistaken beliefs and the heart relinquishing passions that no longer serve moral or spiritual growth. The wistful “If only” underscores how difficult such inner change is compared with nature’s automatic cycles. In Allen’s characteristic ethical-psychological outlook, progress depends on self-scrutiny and the disciplined replacement of error with clearer thought, and of compulsive desire with calmer, more purposeful feeling. The line thus frames self-improvement as continual, seasonal housekeeping of the inner life.