The elixir of life? Some, in ancient times, believed it to be the philosopher's stone. Alchemists across ages and cultures tried to formulate it. Emperors in ancient China sought it to become immortal. Ancient Indian texts call it amrita, loosely described as nectar. Still others thought it was soma rasa, an intoxicating drink popular in ancient India.

But perhaps the Arabs came closest to its real meaning, describing it as aab-e-hayaat (where aab means water and hayaat life). Indeed, water today has become the scarcest essential resource - we are talking about freshwater here.

It is this scarcity that has prompted the Beijing municipal government to look to recycled water to fulfill the city's needs. The local administration has said one-fourth of its water needs, including road cleaning and municipal garden watering, would come from sewage treatment plants. This, by any measure, is a welcome development.

The water crisis, not only in Beijing but also around the world, reminds one of the most precious liquid's importance for human beings - as Stanislaw Lem portrays it in his novel Solaris, or more precisely the way Andrei Tarkovsky philosophizes it in the film of the same name.

Much more than in Lem's novel, Tarkovsky's film makes water the sensual source of life, contrasting it with the space station orbiting the planet Solaris. It is this space station that a psychologist travels to in order to evaluate the confusing messages sent by the crew comprising three members. The psychologist's job is to determine the future of the mission - whether it should continue or be called off.

And this is where water comes into full play. Solaris is a planet almost fully covered with water, an ocean full of organisms with which Earth's scientists try to establish communication. The ocean's response to the terrestrial scientists' attempts to communicate with the organisms exposes the earthlings' secrets, especially their hidden desires and weaknesses.

The investigating psychologist is no different, because he too has hidden desires and guilt. And since every drop of water on Solaris seems to have a brain of its own, his job seems to be all the more difficult - the end in such a philosophical quest is not obvious but not impossible to guess.

Tarkovsky uses the theme of attempted communication between humans and supernatural entities in Stalker, too - replacing the ocean and its organisms in Solaris with the supernatural entity the "zone". But Solaris stands out for giving life independent of all known traits to water. Water, the sacred-most element in all major religions of the world, perhaps has not been given a life of its own by any other filmmaker. Did Tarkovsky do so because of his spiritual beliefs? Possibly.

The "reality" he depicted in his film more than 50 years ago, however, is coming true today. T.S. Eliot, in his poem The Waste Land, says "fear death by water". Maybe it's time to fear death without water.

By the way, this is the 30th year of Tarkovsky's death.