Walden and The Bean-Field

At the conclusion of "The Bean-Field," Henry David Thoreau writes:

The true husbandman will cease from anxiety, as the squirrels manifest no concern whether the woods will bear chestnuts this year or not, and finish his labor with every day, relinquishing all claim to the produce of his fields, and sacrificing in his mind not only his first but his last fruits also.

I'm telling my students today that if they understand this sentence, then they understand the better part of Thoreau.