What is going on in the village on the afternoon of Whit-Monday?

From the text:

Whit Monday had been looked forward to for a month or more. By the afternoon even those who believed in the Unseen were beginning to resume their little amusements in a tentative fashion, on the supposition that he had quite gone away, and with the sceptics he was already a jest. But people, sceptics and believers alike, were remarkably sociable all that day.