It's almost as if Thoreau was thinking how to answer people who objected that he could live his life of simplicity, with no one else to care for, but how could the average family man do this? He attempts to show John Field that he could get himself out from under some of his burdens if he would decrease his wants and rely more on his native abilities. For the same amount that he pays in rent on the run-down Baker place, Field and his family could have a house as cozy as Thoreau's, Thoreau states. Yet Field is unable to benefit from the lesson. It may be a problem of social class and education that keeps Field from realizing that he has other options.
10.6 As I was leaving the Irishman's roof after the rain, bending my steps again to the pond, my haste to catch pickerel, wading in retired meadows, in sloughs and bog-holes, in forlorn and savage places, appeared for an instant trivial to me who had been sent to school and college; but as I ran down the hill toward the reddening west, with the rainbow over my shoulder, and some faint tinkling sounds borne to my ear through the cleansed air, from I know not what quarter, my Good Genius seemed to say -- Go fish and hunt far and wide day by day -- farther and wider -- and rest thee by many brooks and hearth-sides without misgiving. Remember thy Creator in the days of thy youth. Rise free from care before the dawn, and seek adventures. Let the noon find thee by other lakes, and the night overtake thee everywhere at home. There are no larger fields than these, no worthier games than may here be played. Grow wild according to thy nature, like these sedges and brakes, which will never become English bay. Let the thunder rumble; what if it threaten ruin to farmers' crops? That is not its errand to thee. Take shelter under the cloud, while they flee to carts and sheds. Let not to get a living be thy trade, but thy sport. Enjoy the land, but own it not. Through want of enterprise and faith men are where they are, buying and selling, and spending their lives like serfs.
He doesn't often let us in on moments when he struggles with or doubts his choice of life. He has such a doubt here, asking whether he might be wasting himself and his education, until his "Good Genius" restores to him his better sense.