"Here is Rhodes, jump here." From Aesop's Fables #209, "The Boastful Athlete." A man who had been off in foreign lands, returns home. He brags of his exploits. He claims that in Rhodes he made a long jump the likes of which had never been seen. A skeptical bystander calls him on his boast: Here's your Rhodes, jump here!
The moral? Put your money where your mouth is. Don't talk about it, do it!
This post is a stub. Perhaps an erudite classicist such as Mike Gilleland could complete it. He would have to do at least the following: dig up all the ancient sources in Greek and Latin; trace the saying in Erasmus and Goethe; comment on Hegel's variation on the saying in the Vorrede zur Philosophie des Rechts, explaining why he has saltus for salta; find and comment on Marx's comment on Hegel's employment of the saying.
Finally, if Alan Rhoda were to rename his cleverly titled weblog Alanyzer — and I'm not saying he should — he might consider Hic Rhoda, Hic Salta. He is a very tall man; I'm 6' 1'' and had to look up to see his face when I met him in Las Vegas some years back. To jump over him would be quite a feat.