Thomas Aquinas (died 1274), a Dominican friar and the "Doctor Angelicus" of the Catholic Church, says that moderation in wine is sufficient for salvation but that for certain persons perfection requires abstinence, and this was dependent upon their circumstance. With regard to the Eucharist, he says that grape wine should be used and that "must", unlike juice from unripe grapes, qualifies as wine because its sweetness will naturally turn it into wine. So freshly pressed must is indeed usable (preferably after filtering any impurities).