The community fruition of wine begins for the Greeks with a preparation aimed at moderating its alcohol content,

the custom, however, is well known earlier before the birth of the symposium.  The most ancient specific reference to the mixture of wine and water is the controversial passage from Book IX of the Iliad in which Achilles, upon the arrival of the Achaean embassy, ​​exhorts Patroclus to pour it zåróteron, a term which was later considered to be equivalent to "stronger”, with less water (as Luciano uses it), but which in all probability meant "sooner”, as already pointed out by Aristotle in the Poetics.  Achilles' invitation, therefore, was not aimed at offering a more concentrate drink, a hypothetical form of respect for the guests, but rather at urging Patroclus to serve his newly arrived companions.  After the fabulous nectar of Marone in the Odyssey, to be lengthened with twenty measures of water, the indications on the mixture of water and wine are very numerous in Greek poetry.  In Works and Days, Hesiod recommends three parts of water against one part of wine, the same proportion as a passage of Ion of Chios; they indicate a two-to-one ratio of Elk and Anacreon; the latter elsewhere tends to five to three.  The indications provided by the comic theater are very numerous, due to the specific collection of passages contained in the University Deipnosophists: the four to one of Alessie, the five to two of Eupoli are just examples.  Since, however, the comedy dedicates a lot of space to drunkards, the most present measure is that of one-to-one.  Aristophanes' Sausage, the disgusting demagogue protagonist of the Knights, to win the favor of the naive Demo, the personification of the Athenian people, offers him a cup mixed in the ideal proportion between water and wine: three to two.  If you trust a fragment of Xenophanes, it seems that the ancients used to pour the water first and then the wine.  The fact is reported in the Deipnosophists as an opposite procedure concerning the use of the Athenaeum times; Xenophanes, however, speaks of the mixture to be served in the cup, not in the crater ".

In the face of so many different proportions, there is a sense of order in considering Plutarch's treatment in the Symposium Questions when the cheerful and noisy Aristion, also making a comparison with music, explains the saying "drink five or three, not four". Four parts with three parts of water and one part of wine constitutes a rather weak mixture for overly austere people; two doses of water and one of wine, however, can cause the most dangerous drunkenness, that of those who have lost their mind and have not even plunged into the numbness that renders harmless. With the "five", that is the ratio of three to two, on the other hand, a fully harmonious mixture is obtained, bringing calm and tranquility to the soul: lathikēdés ("that makes you forget pain and worries "), Plutarch himself defines it with a term of strong traditional value. The saying commented on by Plutarch is quoted in Greek in the Stico of Plautus: in the final servile banquet the homonymous protagonist thus invites his friend Sagarino to drink, alluding however not the quantity of the mixture, but rather the number of "ciati" (doses) drawn from the crater, that must be odd for good luck; between three and five, however, Stico has no doubts in choosing the highest number, saying that as many cups will be emptied as are the fingers of one hand.  

Source: Luca della Bianca, Simone Beta, Il Dono di Dioniso