志士惜年，贤人惜日，圣人惜时。
有志之士珍惜每一年的光阴；贤德之人，珍惜每一天的光阴；而圣人则会珍惜每一寸的光阴。
The stranger is close to us, insofar as we feel between him and ourselves common features of a national, social, occupational, or generally human, nature. He is far from us, insofar as these common features extend beyond him or us, and connect us only because they connect a great many people.
不要小看孩子，他们比我们想象的要聪明得多。
成功不是成为最好的，而是比昨天更好。
变化是宇宙中唯一不变的东西。
在数学的世界里，想象力比知识更重要。