In Ancient Greece:
Wine was never, ever drunk straight. It was mixed with water in a crockery vessel called the “krater.” A one part wine to one part water mixture was considered dangerous. Even one part wine to two parts water was still considered too strong and barbaric. One part wine to three parts water was seen, by Plutarch at least, as the perfect balance.
– Food In Ancient Greece, Cook’s Info
Wine was almost always diluted, usually with water (or snow when the wine was to be served cold). The Greeks believed that only barbarians drank unmixed or undiluted wine and that the Spartan king Cleomenes I was once driven insane after drinking wine this way. They also believed that undiluted wine could even kill the drinker: the Gallic chieftain Brennus was recorded as having committed suicide by drinking wine full-strength. Greeks asserted that the dilution of wine with water was a mark of civilized behavior, whose contrast was embodied in the myth of the battle of Lapiths with the Centaurs, inflamed to rape and mayhem because of wine drunk undiluted with water.
– Wikipedia: Ancient Greece And Wine
According to Harold McGee, water can be a flavor enhancer because it dilutes harsh or overpowering ingredients, broadening the aroma and flavor range of the final product. This is true for wine (and coffee as he describes) because it dilutes alcohol, a component which, according to chemists can “accentuate a wine’s bitterness, reduce its apparent acidity and diminish the release of most aroma molecules. Alcohol particularly holds down fruity and floral aromas, so the aroma that’s left is mainly woody, herbaceous and vegetal.”
The more I look at the traditional Mediterranean diet, the more I see how healthful it is, and the more I see how utterly unlike it is to the Mediterranean diet being promoted today.