What was it in his school reading that that ceremony with the water indefinitely reminded him of?
Wasn't there some Greek or Roman superstition about shaking your head when water was poured upon it?
What could that superstition be, and what light might it cast on that mysterious ceremony?
He wished he could remember; but it was so long since he'd read it, and he never cared much at school for Greek or Roman antiquities.
Suddenly, in a lull of the rain, the whole context at once came back with a rush to him.

He remembered now he had read it, some time or other, in some classical dictionary.

It was a custom connected with Greek sacrifices.

The officiating priest poured water or wine on the head of the sheep, bullock, or other victim.

If the victim shook its head and knocked off the drops, that was a sign that it was fit for the sacrifice, and that the god accepted it.