Catena Aurea on Matthew 28:1–7: Gregory the Great

Or otherwise; “Lightning” inspires terror; “snow” is an emblem of equity; and as the Almighty God is terrible to sinners and mild to the righteous, so this Angel is rightly a witness of His resurrection, and is exhibited with a countenance as lightning, and with raiment as snow, that by His presence He might terrify the wicked, and comfort the good; and so it follows, “And for fear of him the keepers did shake.”