First: how do we come to understand abstract words?
What is truth, irony, beauty, purple? You can't define these terms by pointing to an example... You can't get the meaning of the word blue across merely by pointing to, say, a blue crayon and announcing, "This is blue." The obvious question then becomes, "What's blue?" Does 'blue' mean crayon, Crayola crayon, tubular object, paper-wrapped thing, or what?
But how do we come to understand such words?