要保持剑的锋利就得时时磨拭，要保持头脑灵光就得看书。

A mind needs books like a sword needs a whetstone.

youdao

我的兄弟有他的长剑、国王罗伯特有他的战锤，而我有的是脑子……头脑要阅读才能保持清醒，就像剑要磨才锋利一样。

My brother has his sword, King Robert has his warhammer, and I have my mind... and a mind needs books as a sword needs a whetstone, if it is to keep its edge.

youdao

我的兄弟有他的长剑、国王罗伯特有他的战锤，而我有的是脑子……头脑要阅读才能保持清醒，就像剑要磨才锋利一样。

My brother has his sword, King Robert has his warhammer, and I have my mind... and a mind needs books as a sword needs a whetstone, if it is to keep its edge.

youdao