This quotation can be viewed in the context of a book
"Youth is not a time of lifeit is a state of mind. It is not a matter of red cheeks, red lips and supple knees. It is a temper of the will; a quality of the imagination; a vigor of the emotions; it is a freshness of the deep springs of life. Youth means a tempermental predominance of courage over timidity, of the appetite for adventure over a life of ease. This often exists in a man of fifty, more than in a boy of twenty. Nobody grows old by merely living a number of years; people grow old by deserting their ideals. Years may wrinkle the skin, but to give up enthusiasm wrinkles the soul. Worry, doubt, self-distrust, fear and despairthese are the long, long years that bow the head and turn the growing spirit back to dust. Whether seventy or sixteen, there is in every beings heart a love of wonder; the sweet amazement at the stars and starlike things and thoughts; the undaunted challenge of events, the unfailing childlike appetite for what comes next, and the joy in the game of life. You are as young as your faith, as old as your doubt; as young as your self-confidence, as old as your fear, as young as your hope, as old as your despair. In the central place of your heart there is a wireless station. So long as it receives messages of beauty, hope, cheer, grandeur, courage, and power from the earth, from men and from the Infiniteso long are you young. When the wires are all down and the central places of your heart are covered with the snows of pessimism and the ice of cynicism, then are you grown old, indeed!"