Wine is one of the two elements absolutely necessary for the sacrifice of the Eucharist. For valid and licit consecration vinum de vite, i.e., the pure juice of the grape naturally and properly fermented, is to be used. Wine made out of raisins, provided that from its color and taste it may be judged to be pure, may be used (Collect. S.C. de Prop. Fide, n. 705). It may be white or red, weak or strong, sweet or dry.

Since the validity of the Holy Sacrifice and the lawfulness of its celebration require absolutely genuine wine, it becomes the serious obligation of the celebrant to procure only pure wines. And, since wines are frequently so adulterated as to escape minute chemical analysis, it may be taken for granted that the safest way of procuring pure wine is to buy it or not at second hand, but directly from a manufacture who understands and conscientiously respects the great responsibility involved in the celebration of the Holy Sacrifice.

If the wine is changed into vinegar, or it becomes putrid or corrupted, if it was pressed from grapes that were not fully ripe, or it it is mixed with such a quality of water that it can hardly be called wine, its use is forbidden (Missale Rom., De Defectibus, tit. iv. 1). If the wine begins to turn into vinegar, or to become putrid, or if the unfermented juice is pressed from the grape, it would be a grievous offense to use it, but it is considered valid matter (ibid., 2).

To conserve weak and feeble wines, and in order to keep them from souring or spoiling during transportation, a small quantity of spirits of mine (grape brandy or alcohol) may be added, provided the following conditions are observed (1) The added spirit (alcohol) must have been distilled from the grape (ex geniminme vitis); (2) the quantity of alcohol added, together with that which the wine contained naturally after fermentations, must not exceed eighteen percent of the whole; (3) the addition must be made during the process of fermentations (S. Romana et Univ. Inquis., 5 August, 1896).