It is in Jesus that the promise of the new prophet is fulfilled. What was true of Moses only in a fragmentary form is now fully realized in the person of Jesus.: He lives before the face of God, not just as a friend, but as a Son; he lives in the most intimate unity with the Father.(page 6)
Ultimately the Introduction of the pope's book is an apologetic to make this point that Jesus is the prophesied prophet of Deuteronomy 18:18-19 and he comes back to this point throughout the book.
I was mentioning this to a friend, who on hearing this said that this struck him as a direct response to Islam that often uses this passage, as well as Jesus' prophesies of sending the Paraclete (Holy Spirit) as pointing to "the Prophet" meaning Muhammad. There are number of examples of this on the internet, I quote from one of them...From the Islamic Voice, which has a detailed apologetic for Muhammad being the prophesied prophet(I qoute only the beginning, go to the web site for the fuller treatment):
An clear cut biblical prophecy for Prophet Muhammad (Pbuh) is found in the fifth Book of Moses. Though much has been written about it, always useful to mention it whenever the subject occurs. The prophecy (in the words of New International Version) reads as follows:
"I will raise up for them a Prophet like you from among their brothers: I will put my words in his mouth, and he will tell them everything I command him. If anyone does not listen to my words that the Prophet speaks in my name, I myself will call him to account." (Devt. 18:18-19)
The following points of the prophecy are worth elaborations with the point of view of comparative religious study, as the Christian brethren are led to be believe that the above prophecy was for Jesus Christ.
I will raise for them: Raising up "is the exact terminology Qur'an has repeatedly used for a prophet: The Arabic equivalent is 'Ba-asa'. Nowhere in the new Testament these words have been used for 'Jesus Christ'.