Many books are dry and dusty, there is no juice in them; and many are soon exhausted, you would no more go back to them than to a squeezed orange; but some have in them an unfailing sap, both from the tree of knowledge and the tree of life. Here I have written about a few of these books which have borne me good company, in one way or another, -- and about their authors, who have put the best of themselves into their work. Such criticism as the volume contains is therefore mainly in the form of appreciation with reasons for it. So I send forth my new ship, hoping only that it may carry something desirable from each of the ports where it has taken on cargo, and that it may not be sunk by the enemy before it touches at a few friendly harbors.