Theophylact of Ohrid

Or thus; As, on the sun rising, the light of the other heavenly bodies seems to be extinguished, though in reality it is only obscured by the greater light: thus the forerunner is said to decrease; as if he were a star hidden by the sun. Christ increases in proportion as he gradually discloses Himself by miracles; not in the sense of increase, or advancement in virtue, (the opinion of Nestorius,) but only as regards the manifestation of His divinity.