Bede the Venerable
Catena Aurea · Lukasevangelium 2
And when the days of her purification according to the law of Moses were accomplished, they brought him to Jerusalem, to present him to the Lord; (As it is written in the law of the Lord, Every male that openeth the womb shall be called holy to the Lord;) 24 And to offer a sacrifice according to that which is said in the law of the Lord, A pair of turtledoves, or two young pigeons. And, behold, there was a man in Jerusalem, whose name was Simeon; and the same man was just and devout, waiting for the consolation of Israel; and the Holy Ghost was upon him.
(ubi sup.) But while each bird, from its habit of wailing, represents the present sorrows of the saints, in this they differ, that the turtle is solitary, but the pigeon flies about in flocks, and hence the one points to the secret tears of confession, the other to the public assembling of the Church.