Augustine of Hippo — as excerpted in the Catena Aurea on Matthew 27:27-30

“(ubi sup.) Hence we understand what Mark means by clothed him with purple; (Mark 15:17.) instead of the royal purple, this scarlet cloak was used in mockery; and there is a shade of purple which is very like scarlet. Or it may be, that Mark spoke of the purple which the cloak contained, though its colour was scarlet.”