When we say that 2 + 2 = 4 or 2 + 3 = 5,

当我们说2+2=4或2+3=5时
we're saying something about numbers that our mind is able to grasp.

我们是在讨论心灵可以掌握的数字
But what are numbers anyway?

但究竟什么是数字呢
They're certainly not physical objects.

它们当然不是实际的物体
It's not as though someday

你不会在某一天
you're going to open up an issue of National Geographic

打开一本国家地理时
where the cover story's going to be "At long last,

发现上面会印着这样的封面故事
explorers have discovered the number two."

探险家们终于发现了数字2
It's not as though the number two is something

数字2不是
that you see or hear or taste or could bump into.

你能看到或听到或尝到或遇到的东西
Whatever the number two is,

不管数字2是什么
it's something that our mind can grasp

它是心灵可以掌握的东西