Watts advises the perusal of the
prefaces and the index of a book, as they both give light on its contents.

The ravenous appetite of Johnson for reading is expressed in a strong
metaphor by Mrs. Knowles, who said, "he knows how to read better than any
one; he gets at the substance of a book directly: he tears out the heart
of it." Gibbon has a new idea in the "Art of Reading;" he says "we ought
not to attend to the order of our books so much as of our thoughts. The
perusal of a particular work gives birth perhaps to ideas unconnected with
the subject it treats; I pursue these ideas, and quit my proposed plan of
reading." Thus in the midst of Homer he read Longinus; a chapter of
Longinus led to an epistle of Pliny; and having finished Longinus, he
followed the train of his ideas of the sublime and beautiful in the
"Enquiry" of Burke, and concluded by comparing the ancient with the modern
Longinus.

There are some mechanical aids in reading which may prove of great
utility, and form a kind of rejuvenescence of our early studies. Montaigne
placed at the end of a book which he intended not to reperuse, the time he
had read it, with a concise decision on its merits; "that," says he, "it
may thus represent to me the air and general idea I had conceived of the
author, in reading the work." We have several of these annotations. Of
Young the poet it is noticed, that whenever he came to a striking passage
he folded the leaf; and that at his death, books have been found in his
library which had long resisted the power of closing: a mode more easy
than useful; for after a length of time they must be again read to know
why they were folded. This difficulty is obviated by those who note in a
blank leaf the pages to be referred to, with a word of criticism. Nor let
us consider these minute directions as unworthy the most enlarged minds:
by these petty exertions, at the most distant periods, may learning obtain
its authorities, and fancy combine its ideas. Seneca, in sending some
volumes to his friend Lucilius, accompanies them with notes of particular
passages, "that," he observes, "you who only aim at the useful may be
spared the trouble of examining them entire." I have seen books noted by
Voltaire with a word of censure or approbation on the page itself, which
was his usual practice; and these volumes are precious to every man of
taste. Formey complained that the books he lent Voltaire were returned
always disfigured by his remark