What do we understand?

In response to Miss Huang's "What do we understand?":

Here's what I really wrote down (embellished a bit).

We understand nothing.

We do not understand the tools we have created for ourselves, which is why accidents happen.

We do not understand ourselves, so we can never satisfy ourselves to find happiness by ourselves.

And we understand, least of all, the people around us, so we shall always be apart.

In everyone's heart, there is an inpenetratable armor like the hedgehog's spines that not only separates us, but also forces us keep our distance lest we destroy one another.