As the Romans did thousands of years ago, so today we continue to hold the ancient classical Greek language in high regard. Among other things, this regard gives us a triad of Greek occasions on the second weekend of March 2015.

One is pi day. Not pie but pi, although many celebrate the day with pies. But this is the Greek pi, standing for perhaps the most famous number in mathematics, the ratio of the circumference of a circle to its diameter. The ancients, starting with Archimedes, figured this number as approximately 22/7, which is pretty close, and as good as they could do considering that they lacked the benefits of the decimal system. We, however, have that benefit, so we can write pi as a number that begins:

3.14

and which by our American custom of putting the month before the day becomes, incidentally, March 14.

This year, however, it gets even better. Add to the number the last two digits of the year 2015, and we have

3.14.15

which is the correct extension of pi to four decimal places. This happens only once in a century.

We could get even fancier and add a particular time of day on the 14th:

3.14.15.9:26:53

Get rid of all colons and decimals except the first, and you have pi correct to the ninth decimal place.

But why pi?

For that, we can thank one William Jones, a Welsh mathematician, who more than 300 years ago began using pi in place of awkward circumlocutions. And why did he give this irrational ratio the name of the 16th letter of the Greek alphabet? Because periphery, the term he used instead of circumference, begins with p. Simple as that.

That’s one special occasion for the second weekend in March. Another is the opportunity to mention triskaidekaphobia, fear of (Friday the) 13th, for the second month in a row. This happens only when the first Friday the 13th occurs in February, and only when February has 28 days so that the numbered days of March come on the same days of the week.

And the third? Well, it’s a possible antidote for or immunization against triskaidekaphobia. It’s known as Carberry Day.
Admittedly, it’s not very well known, except at Brown University. I learned about it from my colleague Adam Blistein, executive director of the Society for Classical Studies, who pointed me to the whole story of Josiah Carberry and Carberry Day, on the website of the John Hay Library at Brown.

Carberry, it appears, was professor of psychhoceramics, the study of cracked pots. He was not encumbered by flesh and blood, but notices of his lectures and publications were regularly posted at Brown. “Those who maintain the Carberry tradition at Brown like to say that the Professor was born on a bulletin board” (in 1929), Blistein explains.

Here’s the library’s story of Carberry Day:

“On Friday, May 13, 1955, an anonymous gift of $101.01 was received by the University from Professor Carberry to establish the Josiah S. Carberry Fund in memory of his ‘future late wife.’ A condition of the gift was that, henceforth, every Friday the 13th would be designated ‘Carberry Day,’ and on that day friends of the University would deposit their lose change in brown jugs to augment the fund, which is used to purchase ‘such books as Professor Carberry might or might not approve of.’”

As a result, Blistein remarks, “to some people, even if those people know Greek, Friday the 13th is a lucky day.”

So let’s give it a try. Fill the brown jug and celebrate!