The Canonists, say Pollock and Maitland (loc. cit.), "made a capricious mess of the marriage law." "Seldom," says Howard (op. cit., vol i, p. 340), "have mere theory and subtle quibbling had more disastrous consequences in practical life than in the case of the distinction between sponsalia de præsenti and de futuro."
Howard, op. cit., vol. i, pp. 386 et seq. On the whole, however, Luther's opinion was that marriage, though a sacred and mysterious thing, is not a sacrament; his various statements on the matter are brought together by Strampff, Luther über die Ehe, pp. 204-214.
Howard, op. cit., vol. ii, pp. 61 et seq.