Painful Beauty

In a book that I'm reading right now, A Severe Mercy, the two main characters have a dialogue about how for both of them, beauty is painful. To witness and see things that are beautiful gives them a longing that cannot be expressed, except in terms of pain. The French philosopher Chardin wrote of how when we witness beauty, it reminds us of something eternal that we have lost, which we desire to recover again.
For me, to read poetry is a sense of something that is not expressed in any other sphere of life. What would drive the great poets to write? Why would Whitman write of the people, why would Yeats write of the poignance of love, why does Dickinson write of eternity, why does Neruda lament over lost and unrequited love. . . . . . . .why are the great ones driven and compelled to express themselves in verse and stanza? Why are we, in all of humanity, driven to create and express? That seems to be an eternal question. . . . . . .