Nobody grows old merely by a number of years. We grow old by deserting our ideals. Years may wrinkle the skin, but to give up enthusiasm wrinkles the soul. 年岁有加，并非垂老；理想丢弃，方堕暮年。岁月悠悠，衰微只及肌肤，热忱抛却，颓废必致灵魂。—Samuel Ullman