In John 1.45 Philip told Nathanael "We have found the one Moses wrote about in the Law...." It is easy to read that and go on reading, but where did Moses write about Jesus? In John 5.46 Jesus makes a simple statement: "If you believed Moses, you would believe me, for he wrote about me." but where did Moses write about Jesus? Everybody seems to know what is being referred to, but what is the passage they have in mind?
There is one place that that Jesus and Philip might have been referring to, Deu 18.15 "The LORD your God will raise up for you a prophet like me from among your own brothers. You must listen to him." This prophet would be different from other prophets, because Moses was unique: "Since then, no prophet has risen in Israel like Moses, whom the LORD knew face to face, who did all those miraculous signs and wonders the LORD sent him to do in Egypt - to Pharaoh and to all his officials and to the whole land. For no one has ever shown the mighty power or performed the awesome deeds that Moses did in the sight of all Israel" Deu 34.10-12. Also in Num 12.6-8 "...when a prophet of the LORD is among you, I reveal myself to him in visions, I speak to him in dreams. But this is not true of my servant Moses; he is faithful in all my house. With him I speak face to face, clearly and not in riddles; he sees the form of the LORD. Why then were you not afraid to speak against my servant Moses?"
When we understand that the people were looking for a prophet like Moses a number of odd passages make a lot of sense. For example in John 1.19-21 the priests and Levites sent from Jerusalem asked John the Baptist if he was the Messiah or Elijah, and they also asked if he was "the Prophet." They didn't ask if he was a prophet, they wanted to know if he was "the Prophet." In John 6.1-14 Jesus fed the multitude and the people said "This is indeed the prophet who is to come into the world." Then in John 7.37-40 Jesus offers "living water" to the people and they say "Surely this man is the Prophet." Why did they react like that? Because Jesus was doing miricles like Moses, feeding the Israelites in the wilderness and offering them water.
A passage that had always puzzled me is in John 7.52, where the Pharisees tell Nicodemus "Are you from Galilee, too? Look into it, and you will find that a prophet does not come out of Galilee." I always wondered what they were talking about. What does it matter where a prophet came from? Jonah came from Galilee (Gath Heper). But if we are talking about the Prophet (as in the NIV footnote) then what they say does make sense: In Mat 2.5-6 "...Bethlehem...out of you will come a ruler who will be the shepherd of my people Israel." The pharisees were saying that Jesus couldn't be the Prophet because they thought he was from Galilee.