And no, it wasn't shame I now felt, or guilt, but something rarer in my life and stronger than both: remorse. A feeling which is more complicated, curdled, and primeval. Whose chief characteristic is that nothing can be done about it: too much time has passed, too much damage has been done, for amends to be made.
Julian Barnes (2011). “The Sense of an Ending”, p.99, Random House