Johnson darted to the shelves and began silently reading the spines of the volumes arrayed there. “Dr. Johnson,” said Cambridge, “it seems odd that one should have such a desire to look at the backs of books.” Johnson, Boswell would later recall, “instantly started from his reverie, wheeled about, and replied, ‘Sir, the reason is very plain. Knowledge is of two kinds. We know a subject ourselves, or we know where we can find information upon it.’”
