"More fitting place I cannot fancy now, For such a man to let the line run off The mortal reel,--such patience hath the Lake, Such gratitude and cheer is in the Pines. But more than either lake or forest's depths This man has in himself: a tranquil man, With sunny sides where well the fruit is ripe, Good front and resolute bearing to this life, And some serener virtues, which control This rich exterior prudence,--virtues high, That in the principles of Things are set, Great by their nature, and consigned to him, Who, like a faithful Merchant, does account To God for what he spends, and in what way. Thrice happy art thou, Walden, in thyself! Such purity is in thy limpid springs,-- In those green shores which do reflect in thee, And in this man who dwells upon thy edge, A holy man within a Hermitage. May all good showers fall gently into thee, May thy surrounding forests long be spared, And may the Dweller on thy tranquil marge There lead a life of deep tranquillity, Pure as thy Waters, handsome as thy Shores, And with those virtues which are like the Stars!" METHODS OF STUDY IN NATURAL HISTORY. VII. I come now to an obscure part of my subject, very difficult to present in a popular form, and yet so important in the scientific investigations of our day that I cannot omit it entirely. I allude to what are called by naturalists Collateral Series or Parallel Types. These are by no means difficult to trace, because they are connected by seeming resemblances, which, though very likely to mislead and perplex the observer, yet naturally suggest the association of such groups. Let me introduce the subject with the statement of some facts.