In the central place of every heart there is a recording chamber. So long as it receives a message of beauty, hope, cheer, and courage — so long are you young. When the wires are all down and our heart is covered with the snow of pessimism and the ice of cynicism, then, and only then, are you grown old.

MacArthur frames youth and age as inner conditions rather than biological facts. The “recording chamber” and “wires” evoke a communications system: as long as the heart remains receptive to messages of beauty, hope, cheer, and courage, a person stays spiritually young—open, resilient, and forward-looking. “Snow of pessimism” and “ice of cynicism” suggest emotional numbness and hardened disbelief; when these shut down receptivity, one becomes “old” in the sense of being closed to renewal. The passage reflects a moral-psychological ideal common in early-to-mid 20th-century rhetoric: character and attitude, not years, determine vitality.