But every time the horse draws the carriage, he uses up so much muscle; and that muscle he must get back again by eating hay and corn; and that hay and corn must be put back again into the land by manure, or there will be all the less for the horse next year.

For one cannot eat one's cake and keep it too; and no more can one eat one's grass.
So this field is a truly wonderful place.

It is no ugly pile of brick and mortar, with a tall chimney pouring out smoke and evil smells, with unhealthy, haggard people toiling inside.

Why do you look surprised?
Because--because nobody ever said it was.

You mean a manufactory.
Well, and this hay-field is a manufactory: only like most of Madam How's workshops, infinitely more beautiful, as well as infinitely more crafty, than any manufactory of man's building.