Oswald does not particularly want his story to be remembered, but he wishes to tell the truth, and perhaps it is what father calls a wholesome discipline to lay bare the awful facts.
It was like this.
On Alice's and Noel's birthday we went on the river for a picnic.

Before that we had not known that there was a river so near us.

Afterwards father said he wished we had been allowed to remain on our pristine ignorance, whatever that is.

And perhaps the dark hour did dawn when we wished so too.

But a truce to vain regrets.
It was rather a fine thing in birthdays.