midnight
`` Because the gray heron does not go southwards in the month of June ; and because he never flies so low . '' `` What has that to say to it ? '' `` I will tell you . I was making the midnight round to relieve the guard at the Porta Latina . From the battlements of the tower I looked out sharply into the night . Nothing was to be seen , and nothing to be heard , except the song of the nightingale . Then suddenly I heard the cry of the gray heron . ''