Q:

Question from Mark Twain's quote

Anger is an acid that can do more harm to the vessel in which it is stored than to anything on which it is poured.

I'm not sure what "anything on which it is poured" actually means.
I looked up the dictionary searching for "pour" and "pour on" and tried to construct the sentence but I got more confused. If you poured the acid on "anything", isn't it the same thing as storing the acid in since the "acid" would still remain? Or is it just the matter of degree?

A:

Anger is compared to an acid. About acid, Twain observes the following:

If you pour acid on something, it is harmful to what you pour it on.
Acid is harmful to the container in which you store it.
If you leave acid in the container (long enough), the harm to the container is greater than to anything you pour it on.

In a similar way you can see anger:

If you are angry at someone (pour your anger at that person), it harms that person.
If you are angry (store your anger inside), it is harmful to yourself.
If you keep angry (long enough), the harm to you is greater than to the person you are angry at.

Pouring acid on something is compared with being angry at someone, in the sense that you can "pour" your anger on someone, or direct your anger at them.

