The following quotations are from “Essays in Idleness” (Kenko, c. 1283-1352):
“If there is no advantage in changing a thing it is better not to change it.” (#127)
“It is a pleasant thing when a person comes without business and leaves after a quiet talk. Joyful, too, to get a letter just asking how you are, after a long silence.” (#170)
“It is always better to be simple and uninteresting than to be interesting but affected.” (#231)
But:
“Somehow there is always a charm about even the most impromptu and careless sayings of the men of bygone days.” (#14)
Kenko can generally be counted upon to say pretty things when provoked. (Essay #191 is “I think it a pity to hear a man say that things do not look their best at night. … Good-looking people look even better at night by lamplight; and it is pleasant to hear the voices of people talking guardedly in the dark. Perfumes and music, too, are most pleasing at night-time.”)
Another tremendous book is Abelard’s The Story of My Misfortunes. (This is the Abelard of Abelard and Heloise (Heloise link a better, shorter, summary)–basically, Abelard shagged Heloise, and then got castrated for it.) Abelard’s this 12th Century genius French philosopher who battles his way through life troubled by not a skerrick of self-doubt. From the Foreword, a note to the reader: “in comparing your sorrows with mine, you may discover that yours are in truth nought”–not only is he smarter everyone else, but his misfortunes are the greater too.
There is an on-line version, but a printed version is probably better. [Update! I love this book so much that I produced some nicely-formatted versions.)