That a conjectural critick should often be mistaken, cannot be
wonderful, either to others or himself, if it be considered that
in his art there is no system, no principal and axiomatical truth
that regulates subordinate positions. His chance of errour is renewed
at every attempt; an oblique view of the passage a slight misapprehension
of a phrase, a casual inattention to the parts connected, is sufficient
to make him not only fail but fail ridiculously; and when he succeeds
best, he produces perhaps but one reading of many probable, and he
that suggests another will always be able to dispute his claims.

It is an unhappy state, in which danger is hid under pleasure. The
allurements of emendation are scarcely resistible. Conjecture has
all the joy and all the pride of invention, and he that has once
started a happy change, is too much delighted to consider what
objections may rise against it.

Yet conjectural criticism has been of great use in the learned world;
nor is it my intention to depreciate a study, that has exercised
so many mighty minds, from the revival of learning to our own age,
from the Bishop of Aleria to English Bentley. The criticks on ancient
authours have, in the exercise of their sagacity, many assistances,
which the editor of Shakespeare is condemned to want. They are
employed upon grammatical and settled languages, whose construction
contributes so much to perspicuity, that Homer has fewer passages
unintelligible than Chaucer. The words have not only a known
regimen, but invariable quantities, which direct and confine the
choice. There are commonly more manuscripts than one; and they do
not often conspire in the same mistakes. Yet Scaliger could confess
to Salmasius how little satisfaction his emendations gave him.