Tried this joke on the family and coworkers today, based on George Santayana's quote.
Short version: "Those who cannot remember the past are condemned to..."
Long version: "Progress, far from consisting in change, depends on retentiveness. When change is absolute there remains no being to improve and no direction is set for possible improvement: and when experience is not retained, as among savages, infancy is perpetual. Those who cannot remember the past are condemned to...".
Then your listener either derails the joke, or says, "repeat it". And you repeat the quote (fragment).