- Recently, I got a nice message from a monk friend telling me he was taking vassa (3 month Rainy Season Retreat) on July 23rd (the Full Moon Day) and wishing me a happy vassa before he goes offline for three months. However, we at Pa-Auk are taking the vassa today on July 24 (the day after the Full Moon Day). The calendars often say it starts on the Full Moon Day, but we don’t do that at Pa-Auk. So who is correct?
We know from the Pātimokkha chant that the new and full moon Uposatha Days are on the 14th or 15h day.
Suṇātu me bhante saṅgho? Ajjuposatho pannaraso, yadi saṅghassa pattakallaṃ, saṅgho uposathaṃ kareyya, pātimokkhaṃ uddiseyya.
This means: “May the venerable ones listen to me, sirs. Today is the uposatha of the fifteenth [fourteenth]. If the venerable ones are ready, we should perform our pātimokkhaṃ uposatha.”Partial translation taken from BMC 2
So what does this mean. In Buddhism we count time in new and full moon cycles. Sometimes it is 14 days and sometimes it is 15 days. The cycle ends on the Uposatha Day, and the new counting cycle starts after the following dawnrise. That is why we start the vassa on the day after the full moon day, and why we end the vassa (pavarana/invitation) on the Full Moon Day. Wikipedia got this correct. Here is a quote below:
Vassa begins on the first day of the waning moon of the eighth lunar month, which is the day after Asalha Puja or Asalha Uposatha (“Dhamma day”). It ends on Pavarana, when all monastics come before the sangha and atone for any offense that might have been committed during Vassa.https://en.wikipedia.org/wiki/Vassa
So now you know when the Buddhist Rainy Season starts and when it ends. The tradition of not going anywhere for three months was started in the Buddha’s time because the monks were often traveling and walking over the farmers’ crops and damaging them. Therefore, the Buddha made a rule that no traveling should be done during this 3 month period. I had done another post before about why vassa is late every so often.