An era which will grow more and more incredible with each passing generation until someday people will say it never could've happened at all.
10 seconds sound clip from the The Roaring Twenties (1939) movie soundboard.
You can hear this line at 00:02:07 in the DVD version of the movie.
Quote context
[...]
- Today, while the earth shakes beneath the heels of marching troops...
- While a great portion of the world trembles before the threats of acquisitive, power-mad men...
- We of America have little time to remember an astounding era in our own recent history..
- You always come into a rathole like that?
[...]