可持续性不是一种趋势，而是我们对未来的责任。
学习的魅力主要在于心灵在获取知识时体验到的满足感。
The chief beauty about time is that you cannot waste it in advance. The next year, the next day, the next hour are lying ready for you, as perfect, as unspoiled, as if you had never wasted or misapplied a single moment in all your life. You can turn over a new leaf every hour if you choose.