"He says a "gentleman" used to be someone who didn't have to work with his hands for a living. It would not be remarkable so say,"Mr. Smith is a gentleman and a scoundrel."
My definition of gentleman: Gentleman you are born; rich you become.
That's GOT to be closer to the root even than Lewis's explanation. (Hey, are we kind of going astray here?) Gens, gentis? Race? "Gentle", like "kind" originally conveying more of the sense of "one of us" (or, for us peasants, "one of them") than anything else. Already in the 16th century, the usage is getting interesting or Hamlet's wry line "A little more than kin, but less than kind," wouldn't have the bite it has. For the Lancashire Poet, "rich" and "righteous" seem closely related, if my failing memory serves me.