When Poseideon Repeats

When this month in the Hellenic calendar repeats itself, how do we know when it is supposed to repeat, and how does it impact the rest of the months when it does? Does it take the place of the month that was supposed to come after and then we go along with the calendar as usual afterwards?

The Hellenic calendar is too short, and every three years (at least according to Athens) you have to add an entire month to make sure the holidays still align with harvests every year. It's a leap year, basically. And you just wedge it in between two months, making a 13 month year, instead of the regular twelve.

Yes, you have Poseideon, then Poseideon B, then Gamelion and you keep going.

AgathonZante wrote:When this month in the Hellenic calendar repeats itself, how do we know when it is supposed to repeat …?

Basically, it's just done to keep things in line with the seasons. This winter, those using the Athenian calendar repeated Poseideon because otherwise this summer's Hekatombaion would be starting before the solstice. The ancient Athenians would have done it to stop the New Year celebrations falling in the middle of the harvest. I repeated my Poseidonios so that my New Year (1 Gamelios) wouldn't fall on the same day as Heliogenna. You could have an elaborate set of rules like the Babylonians developed (preserved in the Jewish calendar) but it's not worth it — they were using that calendar for administration as well as fixing festivals.

What I am asking is: When Poseideon repeats itself, does it take the place of the next month, which would usually be Gamelion? And then you just continue on to the next month, which would be Anthesterion?

It doesn't replace the next month: it increases the number of months in the year to thirteen.