长明灯

长心眼儿:

Literally means:

gain wisdom; grow smarter

Actually means:

心眼儿, a tiny cave in heart, refers to the capacity of thought. (According to Chinese traditional understanding, heart is the organ for thinking; and the more caves in the heart, the smarter is the owner).

The whole phrase means one acquires the ability to think wisely and thus grows smarter and wiser. Commendatory.

心眼儿，指思维能力（按中国的传统认识，“心”是思维的器官）。

长心眼儿，比喻学会动脑筋，使自己变得聪明机警一点。具有褒义色彩。