The famous phrase freeing the slaves in rebel territories is "then, thenceforward, and forever free."
So here we have the "forever" of the now-familiar "forever stamps" completing the idea "free forever."
Maybe you had to be there ... or have taken a lot of useless lit classes.
Anyway, here is the last commemorative stamp:
Have 50 years really gone by since?
You could mail a first class letter with one of these.
Check out the price.
I doubt the 'forever' on my Lady Liberty Forever Stamps meant that I could use it forever, but the 'forever' on the Emancipation Forever Stamps was cleverly drawn from "then, thenceforward, and forever free."
Sometimes a cigar is just a cigar.