According to Tom Batiuk (in a Funky Winkerbean strip), if you take a Hoover and put it out in a field, eventually the effects of weather will cause it to completely disintegrate, proving the statement. Of course, the real source is probably Aristotle, who made a lot of well-founded statements that turned out not to be the case. Even Descartes disbelieved in vacuum. I think it really wasn't until the Michelson-Morley experiment in 1887 that the true vacuity of the vacuum was finally demonstrated (positively or negatively, depending on your definition of "vacuity").