In the second half of her one-woman show The Search for Signs of Intelligent Life in the Universe, Lily Tomlin does a brilliant, half-hour-long sketch about a young wife and mother restlessly seeking fulfillment amid the fads, fashions, and ideologies of the feminist '70s. The sketch is built around a treasure trove of satirical trivia: Everyone wears Birkenstock sandals and Indian cotton drawstring pants, the heroine keeps directing her kids to hit each other with their ''Bataca encounter bats,'' and her husband runs off to male-sensitivity classes. Tomlin gently parodies the post-counterculture delusion that every aspect of life, from sibling rivalry to plant holders, could somehow be made ''liberated.'' And she shows us how, in that madly self-inspecting era, which was fueled by a kind of New Age guilt, the harsher realities like adultery kept rudely poking through. Tomlin has such extraordinary empathy, such a luminous gift for merging with a character's heart, that the sketch becomes a profound and exultant piece of theater.
Onstage, The Search for Signs... remains the single greatest comic performance I've ever seen. Tomlin and her collaborator, Jane Wagner (who wrote and staged the show), did more than create a forum for such wonderful Tomlin characters as the embittered punkette Agnus Angst or Trudy the bag lady, whose cheery, inside-out logic becomes a cracked window onto contemporary consciousness. They found a way to turn Tomlin's comedy into a flowing, poetic experience, a hypnotic cascade of words that tapped the audience's imagination, until we seemed to be leaping, right along with Tomlin, from soul to soul.
In the belated movie version, Tomlin and Wagner second-guess themselves. Making a misguided attempt to ''open up'' the show, they alternate between having Tomlin enact her characters on a bare stage and having her do them with sets and costumes. The arbitrary cutting between the two modes destroys the show's rhythm. We no longer watch it with our mind's eye; it's become just another jumble of sketches. And The Search, great as it is, has dated. It seems trapped in another period, an era of discos and aerobics classes. (Tomlin should turn herself loose on the era that followed.) Still, when she gets rolling, as in that '70s playlet, there can be little doubt that Lily Tomlin is one of the sublime actresses of our time. B