Epochs in the Life of the Apostle John by A T Robertson and published by Classics.
Although the material for writing the life of St John are meagre, yet no other figure in the New Testament - not even St Paul or St Peter - makes such a vivid picture on the mind of every reader. Such a vivid picture though is only possible if one identifies the Beloved Disciples of the Fourth Gospel, with the Elder of the Epistles and the John of the Apocalypse.
After a lifetime of study Robertson was convinced that St John, is the author of all the Johnnine literature and "became an eagle who soared above the clouds in the clear sky of the eternal truth of Christ."