IT is generally agreed that that only is true knowledge which consists of information assimilated by our own minds. Mere disjointed facts kept in our memories have no right to be described as knowledge. It is this understanding that has made many writers jeer at so-called index-learning. Thus, in the seventeenth century, Joseph Glanville, writing in his Vanity of Dogmatizing, says: “Methinks 'tis a pitiful piece of knowledge that can be learnt from an index, and a poor ambition to be rich in the inventory of another's treasure.” Dr. Watts alluded to those whose “learning reaches no farther than the tables of contents”; but then he added a sentence which quite takes the sting from what he had said before, and shows how absolutely needful an index is. He says: “If a book has no index or table of contents, 'tis very useful to make one as you are reading it.”