Wittgenstein makes two strong claims in the (extremely short) Preface to the work of his life, and the most widely read work of his, Tractatus Logico-Philosophicus.
First, “Indeed what I have here written makes no claim to novelty in points of detail; and therefore I give no sources, because it is indifferent to me whether what I have thought has already been thought before me by another.”
And the second, possible only in connection with the first, “the truth of the thoughts communicated here seems to me unassailable and definitive.”
This is, I am afraid (and exhilarated) to say, is how all great books are written. In a great silence with which only eternity is capable to provide us.