The prudent husbandman, after having taken from his field all the straw that is there, rakes it over with a wooden rake and gets as much again. The wise child, after the lemonade jug is empty, takes the lemons from the bottom of it and squeezes them into a still larger brew. So does the sagacious author, after having sold his material to the magazines and been paid for it, clap it into book-covers and give it another squeeze.