What is Phillip afraid to do that Timothy would really like for him to do?

I believe that this question is asking about events in chapter 10.  In chapter 10, Timothy hints to Phillip that Phillip should climb some of the trees in order to harvest a few coconuts.  
The two characters are stranded on a small island.  Their diet has been meager and limited to things that the ocean can provide.  Timothy suggests that the coconuts would be a good variation in their diet.  Timothy is completely willing to climb the trees, but he is simply too old and weak to do it.  On the other hand, Phillip is young, energetic, and physically capable of doing the climb.  The problem is that Phillip is too scared to try.  The climb itself would be scary.  Those trees are tall, but Phillip's fears of the climb are deepened because he is currently blind.