Describe the purposes and the types of literature that had major influences on the 18th century novel.

During the 18th century, the literary period that was most
pronounced was the Neoclassical Period (or the Enlightenment Period).  This period began
around 1660 and extended through 1790.

The classics pieces
that emerged during this period addressed the importance of logic and showed contempt
for concern with superstition.

readability="52">

To a certain extent Neoclassicism represented a
reaction against the optimistic, exuberant, and enthusiastic Renaissance view of man as
a being fundamentally good and possessed of an infinite potential for spiritual and
intellectual growth. Neoclassical theorists, by contrast, saw man as an imperfect being,
inherently sinful, whose potential was limited. They replaced the Renaissance emphasis
on the imagination, on invention and experimentation, and on mysticism with an emphasis
on order and reason, on restraint, on common sense, and on religious, political,
economic and philosophical conservatism. They maintained that man himself was the most
appropriate subject of art, and saw art itself as essentially pragmatic — as valuable
because it was somehow useful — and as something which was properly intellectual rather
than emotional.

Hence their emphasis on proper subject
matter; and hence their attempts to subordinate details to an overall design, to employ
in their work concepts like symmetry, proportion, unity, harmony, and grace, which would
facilitate the process of delighting, instructing, educating, and correcting the social
animal which they believed man to be. Their favorite prose literary forms were the
essay, the letter, the satire, the parody, the burlesque, and the moral fable; in
poetry, the favorite verse form was the rhymed couplet, which reached its greatest
sophistication in heroic couplet of Pope; while the theatre saw the development of the
heroic drama, the melodrama, the sentimental comedy, and the comedy of manners. The
fading away of Neoclassicism may have appeared to represent the last flicker of the
Enlightenment, but artistic movements never really die: many of the primary aesthetic
tenets of Neoclassicism, in fact have reappeared in the twentieth century — in, for
example, the poetry and criticism of T. S. Eliot — as manifestations of a reaction
against Romanticism itself: Eliot saw Neo-classicism as emphasising poetic form and
conscious craftsmanship, and Romanticism as a poetics of personal emotion and
"inspiration," and pointedly preferred the
former.

Here is a reference
from a pdf which provides the main authors of the Neoclassic
Period:

readability="26">

-Restoration Period (1660-1700): 
Sample writers include John Dryden, John Lock, Sir William Temple,
Samuel
Pepys, and Aphra Behn in England. Abroad, representative authors include Jean Racine
and
Molière.
-The Augustan Age (1700-1750): The principal English
writers include Addison, Steele, Swift, and Alexander Pope. Abroad, Voltaire is the
dominant French writer.
-The Age of Johnson (1750-1790):  Major writers
include Dr. Samuel Johnson, Boswell, and Edward Gibbon who represent the Neoclassical
tendencies, while writers like Robert Burns, Thomas Gray, Cowper, and Crabbe show
movement away from the Neoclassical ideal. In America, this period is called the
Colonial Period. It includes colonial and revolutionary writers like Ben Franklin,
Thomas Jefferson, and Thomas
Paine.

I truly hope this
helps. This period was one in which authors felt there was hope for change.  They found
it necessary to speak to the masses.