Why did Timothy try to help Phillip after he discovered he was blind?

In the book The Cay Timothy is a kind
older black man ho is from the Caribbean Islands.  He has been treated rudely by Phillip
on the raft after they had been torpedoed and their ship destroyed.  However, he knows
that Phillip is only a boy and can not take care of
himself.

Because they are the only two that appear to have
survived the ship's destruction with a cat, named Stew Cat, he must be the one to help
the lad.  He recognizes that if he does not teach the boy how to survive and fend for
himself despite his blindness that if something happens to him, the boy would
die.