From Venice, that gorgeous if shabby stage rising from a shimmering sea; from Genoa or Rhodes, the traveler sets sail today and steps ashore in yesterday: a Mediterranean cruise is a time machine. Some five thousand years ago, the Greeks gave birth to "western" civilization on the rims of the nearly landlocked lake they called mare nostrum, our sea, She is the Helen of waters. Desired by all who eye her, she has sung a siren song to sailors from Odysseus to Onassis. The Mediterranean is a cocktail of cultures; for cruising purposes, she encompasses several other seas: the Black, the Aegean, the lonian, the Adriatic, the Tyrrhenian, the Ligurian, and the Alboran, Ships swim into the past from Crete in the east to Spain and Morocco in the west where, beyond the Rock of Gibraltar, they dive off the edge of the earth. The isles of Greece! the isles of Greece Where burning Sappho loved and sung, . . Eternal summer gilds them yet But all, except their sun, is set. Lord Byron, while weeping over the decline of the classic world, walked with plea­sure in the antique streets of Greece's classic cities. So wanderers do today. Perhaps the most seductive site in the Greek islands, Delphi rises from a slope of Mount Parnassus in central Greece, a short bus ride uphill above the tiny ports of Galaxidi and Itea, In the val­ley below waves an ocean of green-gray olive trees half as old as time. Myth meets history in the Sanctuary of Apollo where Pythia sat on a three- legged stool above a fissure in the earth and pronounced while in her trance the ambiguous utterances known as oracles. Farther up the hill, the great theater (second century B.C.E.) and the stadium doze in the afternoon sun and bees buzz in the golden grasses. Such a sight is enough to mold anyone into a mystic. The melancholy of brooding in ruins is nowhere more delicious than on Crete, cradle of the Minoan culture.

For cruisers, the Mediterranean cruise begins or ends in Barcelona: exhaustingly energetic, infectiously gleeful Barcelona, as eternally fanciful as a Picasso portrait. Along the Ramblas, street life plays itself out until early morning (nobody dines in Barcelona until eleven P.M.). Where Ferdinand and Isabella received Columbus on his return from the New World, rock musicians costumed as motorcycle thugs shatter the silence of the small Plaza of the King.