Although we cannot maintain that ancient and modern philosophy are one and
continuous (as has been affirmed with more truth respecting ancient and
modern history), for they are separated by an interval of a thousand years,
yet they seem to recur in a sort of cycle, and we are surprised to find
that the new is ever old, and that the teaching of the past has still a
meaning for us.

III. In the preface to the first edition I expressed a strong opinion at
variance with Mr. Grote's, that the so-called Epistles of Plato were
spurious. His friend and editor, Professor Bain, thinks that I ought to
give the reasons why I differ from so eminent an authority. Reserving the
fuller discussion of the question for another place, I will shortly defend
my opinion by the following arguments:--

(a) Because almost all epistles purporting to be of the classical age of
Greek literature are forgeries. (Compare Bentley's Works (Dyce's
Edition).) Of all documents this class are the least likely to be
preserved and the most likely to be invented. The ancient world swarmed
with them; the great libraries stimulated the demand for them; and at a
time when there was no regular publication of books, they easily crept into
the world.

(b) When one epistle out of a number is spurious, the remainder of the
series cannot be admitted to be genuine, unless there be some independent
ground for thinking them so: when all but one are spurious, overwhelming
evidence is required of the genuineness of the one: when they are all
similar in style or motive, like witnesses who agree in the same tale, they
stand or fall together. But no one, not even Mr. Grote, would maintain
that all the Epistles of Plato are genuine, and very few critics think that
more than one of them is so. And they are clearly all written from the