My curiosity satisfied
A friend of mine claimed that the story stems from Gioachino Rossini. However, Rossini's two areas of expertise were music and cooking. These are exemplary activities, but in neither can success be measured by the truth criterion.
Yesterday, in leafing through the new Yale Book of Quotations, I found the answer. The source of the motif is the German poet and translator Johann Heinrich Voss (1751-1826). In the original the senior scholar's response goes as follows: "Dein redseliges Buch lehrt mancherlei Neues und Wahres. Waere das Wahre nur neu, waere das Neue nur wahr!" "Your garrulous book teaches many things new and true. If only the true were new, if only the new were true!"
Another meme that has long interested me is the following. In the reception of an unwelcome piece of information, there are three stages. 1) It couln't possibly be true; 2) It's true, but unimportant; 3) Oh, everyone has known about that for a long time. A good example is the response to the anthropologist Derek Freeman's discovery that Margaret Mead fabricated much of what she claimed to have found about Samoa. At first, the anthropological Establishment reacted in horror. No such aspersions can possibly be laid at the door of that Icon of American anthropology! Then came, well it's true, but the claim doesn't effect the core of Mead's work, which remains as solid as ever. Now we have reached the third stage: who cares about that now; we've known that for a long time.
Another example is John Boswell's fabrications regarding homosexuality and the Christian church. First it was said that Boswell was an impeccable scholar and nothing possibly could be wrong about his findings. Then it was conceded that there were serious flaws, but the whole still stands. Now, there is tacit agreement that his claims simply do not hold up. It has taken over 25 years to reach that point.
This three-sequence template seems to go back to the Swiss-American scientist Louis Agassiz (1807-1863). His formulation has been summarized as follows: "Agassiz says that when a new doctrine is presented, it must go through three stages. First, people say that it isn't true, then that it is against religion, and, in the third stage, that it has long been known."
I don't know where Agassiz stated this; the summary comes from the German scientist K. E. von Baer, reported in turn by Stephen Jay Gould. The second principle (which did not escape modification in the standard version) has the authentic feel of 19th-century disputes about evolution. True, these have never gone away, but for most reasonable persons the argument that "it's against my religion" does not seem conclusive.