On the other hand, you will find at the other extreme of intelligence, among your clientage of readers, those who are completely familiar with books and their uses. There are some readers frequenting public libraries, who not only do not need assistance themselves, but who are fully competent to instruct the librarian. In meeting the calls of such skilled readers, who always know what they require, it is never good policy to obtrude advice or suggestion, but simply to supply what they call for. You will readily recognize and discriminate such experts from the mass of readers, if you have good discernment. Sometimes they are quite as sensitive as they are intelligent, and it may annoy them to have offered them books they do not want, in the absence of what they require. An officious, or super-serviceable librarian or assistant, may sometimes prejudice such a reader by proffering help which he does not want, instead of waiting for his own call or occasion. Let us look at a few examples of the numerous calls at a popular library. For example, a reader asks to see a book, giving an account of the marriage of the Adriatic. You know that this concerns the history of Venice and its Doges, and you turn to various books on Venice, and its history, until you find a description of the strange festival. It may be, and probably is the case, that the books, like most descriptive works and narratives of travellers, are without index. This is a disability in the use of books which you must continually encounter, since multitudes of volumes, old and new, are sent out without a vestige of an index to their contents. Some writers have urged that a law should be made refusing copyright to the author of any book who failed to provide it with an index; a requirement highly desirable, but also highly impracticable. Yet you will find in most books, a division of the contents into chapters, and in the beginning of the volume a table of the contents of each chapter, giving its leading topics. This is a substitute for an index, although (not being arranged in alphabetical order) it is far less useful than that time-saving aid to research. But you have to learn to take advantage of even poor and inferior helps, when you cannot have the best, (as a poor guide is better than no guide at all, unless it misguides,) and so you run your eye quickly through the table of contents to find what you seek. In the case supposed, of the ceremony at Venice, you will be aided in the search by having in mind that the catch-words involved are "Adriatic," and "Doge," and as these begin with capital letters, which stand out, as it were, from the monotonous "lower case" type (as printers call all the letters that are not capitals) your search will be much abridged by omitting to read through all the sentences of your table of contents, and seizing only the passage or passages where "Doge," or "Adriatic," may occur.