If someone is sadder but wiser after a bad experience, they have suffered but they have also learned something from it.

如果某人经历过一次不好的事情之后sadder but wiser，那么就是说他们虽然吃了苦头但是也从中收获了经验。吃一堑，长一智

After the accident, I was sadder but wiser, and would never make the same mistake again.

事故发生后，我吃一堑长一智，我再也不会犯同样的错误了。

The divorce left him a sadder but a wiser man.

离婚让他吃一堑，长一智。