Commenting on the very late origin of the reservation of the consecrated Host for worship in Catholic practice outside the celebration of Mass, Catholics
Both ancient history and present practice of reservation of the Blessed Sacrament stresses that viaticum is its first and principal end [of reserving the Eucharist]. The church organized the worship of the Eucharist outside Mass only in the twelfth century after the controversies over the real presence. Formerly, as we have seen, the Eucharist was reserved only with a view to communion; but this primarily concerned viaticum. (Noèle Maurice Denis Boulet and Roger Béraudy, The Church at Prayer, volume 2: The Eucharist, ed. A.G. Martimort [trans. Damian Smyth, Miriam Hederman, and Daniel Farrelly; Shannon, Ireland: Irish University Press, 1973], 220-21; comment in square brackets added for clarification, emphasis in bold added)
