TODAY marks 15 years since an assassin’s bullet killed my friend, Yitzhak Rabin, the Israeli prime minister. Since his death, not a week has gone by that I have not missed him. I loved him and his wife, Leah, very much. On the occasion of the anniversary of his death, his yahrzeit, the world would do well to remember the lessons of his life: his vision for freedom, tolerance, cooperation, security and peace is as vital now as it was 15 years ago, when he happily spoke and sang for peace at a huge rally in Tel Aviv just before he was killed.