Gregorian

Tom listened to Gregorian chant.

The summer solstice takes place every year around June 21 of the Gregorian calendar.

Many people around the world thought Saturday, July 7th, 2007, might be the luckiest day of the century. That's because in the Gregorian Calendar, it was the seventh day of the seventh month of the seventh year. This might explain why about three times as many weddings were reported that day in the U.S. as for a typical Saturday in July. On the other hand, the 13th day of July falls on a Friday — a coincidence many believe brings bad luck. Why are these numbers so meaningful to some people?

The dates of Hanukkah are based on the Hebrew month of Kislev, which usually falls sometime in November or December in the Gregorian calendar.

The Gregorian calendar is based on the solar cycle.

A new year of the Gregorian calendar will start soon.

A new year of the Gregorian calendar will soon begin.

An average Gregorian year is 365.2425 days.

Also, the play now opens and closes with a chant (definitely not gregorian, as that may have required some research) of Kyrie Eleison four times, not three, which is just enough to confound any Catholic in the audience and make Brecht roll over in his grave and puke.