"Fifteen whole days' work."
"And what did he live on during that time?"
"He had provisions."
"What happened to the hatchet?"
"It was blunted by the work."
"Yes; but you perhaps do not know this: that at the moment when Robinson was beginning the work he perceived a plank thrown by the tide upon the seashore."
"Happy accident! he of course ran to appropriate it?"
"That was his first impulse; but he stopped short, and began to reason thus with himself:—
"'If I appropriate this plank, it will cost me only the trouble of carrying it, and the time needed to descend and remount the cliff.
"'But if I form a plank with my hatchet, first of all, it will procure me fifteen days' employment; then my hatchet will get blunt, which will furnish me with the additional employment of sharpening it; then I shall consume my stock of provisions, which will be a third source of employment in replacing them. Now, labour is wealth. It is clear that I should ruin myself by appropriating the shipwrecked plank. I must protect my personal labour; and, now that I think of it, I can even increase that labour by throwing back the other plank into the sea.'"