Charles H. Duell was the Commissioner of US patent office in 1899. Mr. Deull's most famous attributed utterance is that "everything that can be invented has been invented." Most patent attorneys have also heard that the quote is apocryphal.
In his 1989 article, Samuel Sass traced the quote back to 1981 book titled "The Book of Facts and Fallacies" by Chris Morgan and David Langford. Sass did his work well before Gore created the Internets, so I decided to take a fresh look at the research using Google. The following chart was created based on Google's electronic compilation of 12 million books. The chart shows the frequency that the phrase "everything that can be invented" shows up in the corpus, grouped by the year of publication of each book. The chart shows that Mr. Sass is largely correct in his assessment. Google has no reference to the quote prior to 1980 in its ngram database.
However, with a bit more searching, I came across an 1899 edition of Punch Magazine that had been donated to Harvard University by the Pulitzer family. In that edition, the comedy magazine offered a look at the "coming century." In colloquy, a genius asked "isn't there a clerk who can examine patents?" A boy replied "Quite unnecessary, Sir. Everything that can be invented has been invented."
I suspect that 1899 joke is the origin of the expression. Of course, there is still Ecclesiastes.