Gregory the Great — as excerpted in the Catena Aurea on John 20:10-18

“(Hom. xxv.) We must observe that Mary, who as yet doubted our Lord’s resurrection, turned back to see Jesus. By her doubting she turned her back, as it were, upon our Lord. Yet inasmuch as she loved, she saw Him. She loved and doubted: she saw, and did not recognise Him: And saw Jesus standing, and knew not that it was Jesus.”