To the inevitable question, What are the marks of great literature? no
positive answer can be returned. As a tree is judged by its fruits, so is
literature judged not by theory but by the effect which it produces on
human life; and the judgment is first personal, then general. If a book has
power to awaken in you a lively sense of pleasure or a profound emotion of
sympathy; if it quickens your love of beauty or truth or goodness; if it
moves you to generous thought or noble action, then that book is, for you
and for the time, a great book. If after ten or fifty years it still has
power to quicken you, then for you at least it is a great book forever. And
if it affects many other men and women as it affects you, and if it lives
with power from one generation to another, gladdening the children as it
gladdened the fathers, then surely it is great literature, without further
qualification or need of definition. From this viewpoint the greatest poem
in the world--greatest in that it abides in most human hearts as a loved
and honored guest--is not a mighty _Iliad_ or _Paradise Lost_ or
_Divine Comedy_; it is a familiar little poem of a dozen lines,
beginning "The Lord is my Shepherd."

It is obvious that great literature, which appeals to all classes of men
and to all times, cannot go far afield for rare subjects, or follow new
inventions, or concern itself with fashions that are here to-day and gone
to-morrow. Its only subjects are nature and human nature; it deals with
common experiences of joy or sorrow, pain or pleasure, that all men
understand; it cherishes the unchanging ideals of love, faith, duty,
freedom, reverence, courtesy, which were old to the men who kept their
flocks on the plains of Shinar, and which will be young as the morning to
our children's children.

Such ideals tend to ennoble a writer, and therefore are great books