戒酗酒，酗酒伤神；戒色欲，贪色灭精神；戒美味，美味使精神昏沉；戒过饱，过饱使精神郁闷；戒多动，多动使精神混乱；戒多话，多话损伤精神；戒多忧，多忧使精神郁结；戒多思，思虑多刺激精神；戒久睡，久睡使精神疲倦；戒久读，久读使精神苦劳。

The historian's first duty is to tell the truth as he sees it, regardless of whom it pleases or displeases.

The mind grows by exercise, not by passive absorption.

智力不仅仅是推理的能力；它还包括在记忆中寻找相关材料并在需要时调动注意力的能力。