Strictly speaking, it is impossible to authenticate any painting to the extent of naming the artist who produced that object. One can only increase the likelihood thereof. In one celebrated case I felt I had fully proved that Manets palette had indeed been used to paint a particular painting but a “scholar” on whose reaction the art world depends for final acceptance of authenticity only said “someone” could have borrowed Manets palette one fine day and painted that picture. In a second celebrated case I was able to prove, but not convince, the world that a particular painting (Shroud of Turin) was, in fact, a painting and not an artifact produced by some other mysterious means, e.g., some sort of photographic process or resurrection itself.