Justin Taylor posted this link a few years back and I was pleased to discover it today.
In his article Think Bigger he says:
He goes on to say:
If you want to catch a glimpse of the Trinity as the big story behind the Bible, the best thing to do is to read the Gospel of John fast, in one sitting. Your dominant impression during the first half will be that the Father and the Son love each other, and in the second half the Holy Spirit will burst into your attention as the fulfillment of the revelation.
The Trinity is a biblical doctrine, therefore, in a very special sense: not in any one verse, but as the key to the entire book.