Over the past four or five years I found my self spending more and more time studying in the Gospel of John. The more I study it, the more I discover, and the more questions I have. Whether Augustine or Pope Gregory the Great said it first we will never know, but the more I study John the more I agree that it is “a stream in which a child can wade and an elephant can swim.”
I am going to recommend a work published this year that guides a reader through the “deep waters where elephants swim.” The work is written by Paul N. Anderson and is titled The Riddles of the Fourth Gospel. Fortress Press is the publisher. The ISBN is 978-0-8006-0427-1. Here is a link to the book on Amazon.
I have found the text very useful in my studies of the deep water areas of John and I know you will as well.