How does Foer examine the importance of memory?

In Chapter 11, Yankel writes on the ceiling so that he will know who he is, even as his memory fades. It is sad and strange that he must remind himself, "You are Yankel. You love Brod" every night before bed. Everything, even love, can be forgotten in less than a day's time (especially if one is old). For a healthy person, can love outlast memory? Memory, at least, can be the key to love. Jonathan may find something of family love on his journey by unlocking memories and drawing closer to his ancestors.