God the Invisible King

And it may further be suggested that the extreme aloofness and inhumanity, which is logically necessary in the idea of a Creator God, of an Infinite God, was the reason, so to speak, for the invention of a Holy Spirit, as something proceeding from him, as something bridging the great gulf, a Comforter, a mediator descending into the sphere of the human understanding. That, and the suggestive influence of the Egyptian Trinity that was then being worshipped at the Serapeum, and which had saturated the thought of Alexandria with the conception of a trinity in unity, are probably the realities that account for the Third Person of the Christian Trinity. At any rate the present writer believes that the discussions that shaped the Christian theology we know were dominated by such natural and fundamental thoughts.