In the last few bars of Liszt's masterpiece, Liszt actually wrote a crescendo which can't possibly be played on the piano. I don't know how to interpret it. How do you approach it? Is that more of a gesture thing (like putting more weight on the keys after having played the notes)? 

[![enter image description here](https://i.stack.imgur.com/C21bs.png)](https://i.stack.imgur.com/C21bs.png)