Issur Danielovitch celebrated his 90th birthday Saturday - hardly a show-stopping announcement, except that Danielovitch, the son of poor, illiterate Russian immigrants to America, would later change his name, upon arriving in Hollywood, to Kirk Douglas. The birthday celebration, at a fashionable French restaurant not far from the movie studios that made him famous, was a private affair of sorts, with close to 100 family members and close friends in attendance, according to spokeswoman Annabelle Stevens. The guests included Douglas' wife, Anne, who marked the couple's 50th wedding anniversary two years ago by converting to Judaism. "It was about time he married a nice Jewish girl," she remarked at the time. Also on hand were the nonagenarian's three sons and their families, including actor-producer Michael Douglas and his wife, Catherine Zeta-Jones, all of whom serenaded the patriarch with lyrics set to tunes from Fiddler on the Roof. Among the other well-wishers were Nancy Reagan, Merv Griffin and Don Rickles. In his heyday, Douglas was known for his ego, super-sized even by Hollywood standards, and as a loner and womanizer of epic proportions. He also made 87 movies, among them such favorites as Champion, The Bad and the Beautiful, Lust for Life, Paths of Glory and Spartacus. In Cast a Giant Shadow, one of three films he made in Israel, Douglas portrayed American colonel Mickey Marcus, who lost his life fighting in Israel's War of Independence. After decades of ambivalence about his Jewish background, Douglas has returned with full intensity to a religious heritage he never abandoned but rarely practiced. The wake-up call came in 1991, when the helicopter in which he was riding crashed, killing two young companions and leaving the actor with a severely compressed spine. A few years later, Douglas suffered a debilitating stroke, which left him literally speechless, an actor's worst nightmare. He painfully taught himself to speak again. While wrestling with these afflictions, and even contemplating suicide, "I came to believe that I had been spared because I had not yet come to terms with my Judaism, that I had never come to terms with what it means to be Jewish," Douglas told me at his Beverly Hills home some time ago. He embarked on an intense course of Torah study with Orthodox and Conservative rabbis, wrote two autobiographies and a children's book on the Holocaust, and is supporting numerous Israeli, Jewish, educational and medical causes. As befits his more mature years, Douglas issued a manifesto on his 90th birthday addressed to Generation Y, introducing himself as having survived "World War II, a helicopter crash, a stroke and two new knees." He urged the younger generation "to rebel, to speak up, write, vote and care about people" - because, he wrote with capital-letter emphasis, "THE WORLD IS IN A MESS." "You are the group facing many problems: abject poverty, global warming, genocide, AIDS and suicide bombers," Douglas continued. "We have done very little to solve these problems. Now we leave it to you. You have to fix it, because the situation is intolerable. When I blow out my candles ... it will take a long time, but I'll be thinking of you." Douglas will expand on these thoughts in his ninth book, Let's Face It: 90 Years of Living, Loving and Learning, to be published in March. Even in his more hedonistic days, when he frequently starred as a Nordic-looking action hero slaying legions of Romans and Vikings, Douglas always knew he was a Jew. As he recounted during his second bar mitzva at age 83, "I always fasted on Yom Kippur. I still worked (on the movie set), but I fasted. And let me tell you, it's not easy to make love to Ava Gardner on an empty stomach."