Ambrose of Milan — as excerpted in the Catena Aurea on Luke 1:15-17

“For never is the spirit without power, nor power without the spirit. And therefore it is said, in the spirit and power; because holy Elijah had great power and grace. Power, so that he turned back the false hearts of the people to faith; power of abstinence, and patience, and the spirit of prophecy. Elijah was in the wilderness, in the wilderness also was John. The one sought not the favour of king Ahab; the other despised that of Herod. The one divided Jordan; the other brought men to the Saving waters; John, the forerunner of our Lord’s first coming; Elijah of His latter.”