[1]Being based on the original works does not by itself
grant authenticity; what you do with them is equally and even more
important. Would a marxist interpretation of Plato be authentic, if
based just on the dialogues and not to secondary literature? On the
other hand, a person who understands Plato would offer an authentic
reading, even when using secondary sources together with the original.
Even if secondary literature is set aside, cultural presuppositions,
personal taste and intelligence, etc., would still exert their influence
on the study. Since a reading-void is impossible, authenticity is
achieved by scholars and is estimated by their readers according to their
paideia / kinship with the author they study – it can not be ‘proved’.
[2]There are no “questions of permanent significance and
value” for all humanity, otherwise there wouldn’t have existed a single epoch,
country or person, with no interest to these questions. Greek philosophy
is important inside the Greek-European civilization. Empedocles'
metaphysics are of no essential interest to a buddhist, for example.