In a recent interview, Pope Francis invoked St. Vincent of Lérins in relation to the concept of doctrinal development — especially as a remedy to what the Pope called indietrismo (an attitude of “being backward-looking”) among some Catholics. He has done so previously. The linkage of doctrinal development to Vincent of Lérins may come as a surprise for two reasons. One is that the concept is commonly linked to St. John Henry Newman, and the other is that Vincent is most famous for a quotation that some might take as rejecting doctrinal development.