Few things reflect the duality of modern Jewish existence more than our relationship to the Gregorian calendar. That's right, the Gregorian calendar - the same calendar that will change its numeral on Thursday. The calendar that feels significantly different in Israel than in the Diaspora. One of my favorite aspects of this country is that it runs according to a Jewish rhythm, a Jewish calendar, a Jewish clock. Even the non-religious - let alone the non-Jews - can't escape it. "Jewish time" here means much more than just arriving late: Friday is lax; Shabbat is Shabbat; Sunday we work. For immigrants, that Sunday-work routine takes some getting used to, and is a constant source of whining and yearning. Ask any number of happy, satisfied, well-adjusted immigrants what they miss most about the old country, and nine times out of 10 they will say Sunday. BUT IT'S not only Sunday, it's also New Year's Day that takes on a whole different meaning in Israel. Granted, "Sylvester," as it is known here, has increased in visibility over the years, but it still enjoys nowhere near the status it has abroad. Sylvester. What a name for a holiday. It's like calling Rosh Hashana Myron. I remember being at a loss the first time I heard New Year's called "Sylvester." My mind conjured up film stars portraying boxers (Sylvester Stalone), and lead vocalists singing about everyday people (Sylvester "Sly" Stone). The New Year's Eve I come from was one of banging pots and pans, unfulfilled expectations, football games and onion dips. Mostly it was pretending to have fun. But then I came here and met Sylvester. I read about hotels losing kashrut certificates if they had Sylvester parties, learned that Sylvester was a fourth-century pope responsible for all kinds of anti-Semitism, discovered that January 1 in antiquity was always a good time to kill Jews. I was stunned. ACCORDING TO the Jewish literacy Web site SimpleToRemember.com, "Caesar celebrated the first January 1 New Year by ordering the violent routing of revolutionary Jewish forces in the Galilee. Eyewitnesses say blood flowed in the streets." And there's more: "On New Year's 1581, [Pope] Gregory ordered his troops to confiscate all sacred literature from the Roman Jewish community. Thousands of Jews were murdered in the campaign." All of which, obviously, takes some of the joy out of the celebrations, adds a degree of guilt to participating in Tennyson's "ringing out the old, ringing in the new." This also goes a long way toward explaining this country's ambivalence to the day. Indeed, Israel is the only country that uses the Gregorian calendar but does not mark New Year's Day as a public holiday. This ambivalence extends not only to New Year's Day itself, but to the whole Gregorian calendar, reflected in the many kids in this country who celebrate their Hebrew birthdays and not their secular ones; as if the Hebrew date is the one that matters - the real one - and the Gregorian one is, well, "just because." This double-birthday business can cause confusion. The Wife and I, Diaspora born and bred, feel a connection to our secular birthdays and continue to celebrate them. In fact, I didn't know my Hebrew birthday until I made aliya, and the Interior Ministry put it on my identification card. But for our Israeli-born kids, things are different - they insist on celebrating the Hebrew date. And it drives my dad nuts. He'll call on a day he naively thinks is one of their birthdays, only to find a child who doesn't understand why in the world he is singing "Happy Birthday." "Teach your boy when his birthday is, son," my father once instructed. "Teach him the regular day; someday he might need to know that." All of which reflects the inherent Jewish identity crisis from time immemorial: Are we Jews or regular people? The battle over the birthdays is really a battle between our Jewish and universal selves. This tension does not exist only on the playing field of birthday celebrations. Take a look at the Hebrew newspapers for the date, and you'll find that the Jewish date appears in text form, all spelled out real nice, giving it a certain status. The secular date is written in shorthand. It's numerical, stark, cold, bland: 28.12.08. It's second class. It has also led to a degree of secular calendar illiteracy. Much has been written recently about how Israeli students are falling behind in math, science and English. But that's nothing. I would ask why they don't even seem to know the Gregorian months of the year. FOR YEARS I secretly worried about the intellectual development of my offspring, nervous over their inability to recite the names of the Gregorian months until well into their schooling. I'm talking about teenagers getting confused during the "August, September, October, November" part of the calendar. Months for them don't have names, but numbers. Spring doesn't start in March, but in the third month. School doesn't end in June, but in the sixth month. The rains don't generally start in November, but in the 11th month. This lack of basic knowledge bothered me no end. Luckily, I was comforted by friends who assured me that their kids also didn't know the names of the months. Phew, I wasn't alone. Plus, as these friends pointed out with Zionist pride, at least the kids can recite the Hebrew months. And as well they should: Those months are spelled out in the paper.