When you're depressed, It always helps to lean your head on your arm. Arms like to feel useful.

数学不仅仅是关于数字、方程、计算或算法：它是关于理解的。

A forest is more than a collection of trees; it's a living, breathing ecosystem that sustains life.

"The major threats to survival that our ancestors faced - predators, starvation, disease - left their mark on our fears and anxieties."