Challenge: Melville or Thoreau?

Which, among the sons of Emerson, wrote thusly (no cheating via a robust search engine!):

Zeno, the Stoic, stood in precisely the same relation to the world that I do now. He is, forsooth, bred a merchant....He strolls into a shop and is charmed by a book by Xenophon--and straightway he becomes a philosopher. The sun of a new life's day rises to him....And still the fleshly Zeno sails on, shipwrecked, buffeted, tempest-tossed; but the true Zeno sails ever a placid sea. Play high, play low,--rain, sleet, or snow,-- it's all the same with the Stoic....When evening comes he sits down unwearied to the review of his day,--what's done that's to be undone,--what not done at all still to be done . Himself Truth's unconcerned helpmate.  Another system of book-keeping this than that the Cyprian trader to Phoenicia practiced!