Walden

The only advice I see in the second paragraph is directed at writers. Note, he makes this more of a requirement than a form of advice. Thoreau encourages writers to write an account of their own lives.... not merely the tales they've heard regarding the lives of others. He also cites this writing should be sone in a personal way, as if the writer is addressing a member of his/her own family.

Moreover, I, on my side, require of every writer, first or last, a simple and sincere account of his own life, and not merely what he has heard of other men’s lives; some such account as he would send to his kindred from a distant land; for if he has lived sincerely, it must have been in a distant land to me.