The tightest piece of reasoning in the corpus, and Neville runs it as a chain. God is begetting himself; when God begets himself the self-begotten is still God, because he is not begetting another. But the one begetting is by definition a father and the one begotten is by definition a son - so the Son can say I and my Father are one. And now the chain closes on itself: if the self-begotten is one with the begetter, and the begetter is a father, then the self-begotten though Son must also be Father. Which raises the question the whole catalogue turns on - where, then, is my son? And David appears and calls you Father, fulfilling Psalm 89 (I have found David and he has cried unto me, thou art my Father, my God and the Rock of my salvation) and Psalm 2 (thou art my Son, today I have begotten thee). So David is not an extra character but the proof the argument requires, set up in the beginning of time to show that what was given was fatherhood itself. Related motifs hold the pieces - M827 the shaping of the unbegotten, M854 Malachi's where is my honour, M719 David is my son, M754 if David calls him Lord - and this one holds the inference that joins them. About nineteen lectures carry 'begetting himself'.