Swimming was something of which we knew nothing.

We were already too far removed from the lower life-forms to have the instinct for swimming, and we had not yet become sufficiently man-like to undertake it as the working out of a problem.
I roamed disconsolately up and down the bank, keeping as close to him in his involuntary travels as I could, while he wailed and cried till it was a wonder that he did not bring down upon us every hunting animal within a mile.
The hours passed.

The sun climbed overhead and began its descent to the west.

The light wind died down and left Lop-Ear on his log floating around a hundred feet away.

And then, somehow, I know not how, Lop-Ear made the great discovery.