"Haven't we met someplace before?" is a popular (but often insincere) introduction. It's also an earnest and commonly asked question by Jews when meeting other Jews. Why do we often feel as if we’ve met before and why do we care?

As Jews, we have an affinity for other Jews. My mother keeps a mental list of Jewish celebrities and athletes. She says things to my father like, "Irving, did you know that James Brolin is Jewish?" My dad then looks up and replies, "Miriam, no he's not.”

My mom isn’t the only one who collects and catalogues Jews. My kids are huge fans of the Adam Sandler Chanukah songs. Why? What makes his lyrics strike a chord? The words to his melodies chronicle famous Jews in American society. Would a similar song for Lutherans or Baptists find an audience? I don't think so.

I love talking to strangers on trains, buses, taxis, grocery stores and beauty salons. It makes otherwise mundane situations intriguing. I can discuss almost anything with anyone. If I think there’s a remote possibility, I try to figure out if my victims are Jewish. Why? I have a theory.

The holiday of Shavuot is one of the three pilgrimage festivals. Compared with its sister holidays, Sukkot and Pesach, there are few rituals associated with Shavuoth. On Sukkot we build a booth and use a lulav and etrog with specific guidelines. On Passover, we clean like crazy, ridding our homes of the chametz and then participate in Seders steeped in pageantry and ritual. On Shavuoth it’s customary to eat dairy foods and stay up all night studying Torah. Easy stuff contrasted to what is expected of us on Sukkot and Pesach. Shavuoth is a holiday where we kind of sit back and appreciate what we've been given-- the harvest and biggest gift of all--The Torah.

On Shavuoth, G-d revealed himself to all of Israel. Previously, he was known only to individuals - Abraham and Moses. If G-d hadn't declared Himself to all Jews, then this nation of skeptics would have doubted His existence. G-d gave the Torah directly to all Jews at Mount Sinai, even those who were not yet born. Thus, in a mystical sense, we were all together for a moment in history. Each of us stood at Sinai regardless of our level or religiosity, gender, income or any other extraneous factors. We were all there as Jews.

Perhaps connecting with other Jews is a collective attempt to recapture that incredible experience when we were all in the same place. When meeting another Jew there’s an indefinable connection that can’t be adequately described with words.

Maybe we actually did meet before. Possibly the Jewish man next to you on the subway in New York or the little girl on the bus in Israel may have stood beside you at Sinai, and maybe that’s the bond that’s so difficult to define.

Deborah Biskin Levine is a freelance writer in Albany, New York. Her first book is entitled Acts of Lovingkindness (JPS).