people who live _for_ science or poetry, it goes its way earnestly and
quietly, but extremely slowly; and it produces in Europe scarcely a
dozen works in a century, which, however, are _permanent_. The other
literature is pursued by people who live _on_ science or poetry; it goes
at a gallop amid a great noise and shouting of those taking part, and
brings yearly many thousand works into the market. But after a few years
one asks, Where are they? where is their fame, which was so great
formerly? This class of literature may be distinguished as fleeting, the
other as permanent.

* * * * *

It would be a good thing to buy books if one could also buy the time to
read them; but one usually confuses the purchase of books with the
acquisition of their contents. To desire that a man should retain
everything he has ever read, is the same as wishing him to retain in his
stomach all that he has ever eaten. He has been bodily nourished on what
he has eaten, and mentally on what he has read, and through them become
what he is. As the body assimilates what is homogeneous to it, so will a
man _retain_ what _interests_ him; in other words, what coincides with
his system of thought or suits his ends. Every one has aims, but very
few have anything approaching a system of thought. This is why such
people do not take an objective interest in anything, and why they learn
nothing from what they read: they remember nothing about it.

_Repetitio est mater studiorum_. Any kind of important book should
immediately be read twice, partly because one grasps the matter in its
entirety the second time, and only really understands the beginning when
the end is known; and partly because in reading it the second time one's
temper and mood are different, so that one gets another impression; it