In the mid 70s there was a popular novel-- middle-brow fiction, my mind says, about the level of The Magus-- that had an epigraph in French, more or less to the effect of 'There are men who spend their time measuring the Pyramids and (something else) which is sufficient demonstration of the melancholy of existence.' All that I remember of the French (given my track record in these matters, 90% for sure remembering wrong) is 'une grande preuve de la melancolie.' De vivre? De la vie? De l'existance? Dunno.
Mind links the book to Fowles, but possibly only because I may have read The French Lieutenant's Woman around the same time. Book was popular enough that my friends could quote that at each other. It doesn't *sound* like a FLW epigraph and it definitely came at the start of the book along with a couple of other quotes.
Has anyone ever run across this? It's only been bothering me for about 30 years.