04/24/2011 06:31 pm ET | Updated Jun 30, 2011

Great Opera Singers Visit What's My Line?

Long before the debut of People Magazine on March 4, 1974, one of the most popular forms of celebrity appearances was the "Mystery Guest" spot on What's My Line? The popular television game show originally ran on CBS from 1950 to 1967 with former television newsman John Charles Daly as its host.

During the "Mystery Guest" segments, the panel was required to wear blindfolds to prevent them from recognizing the mystery guest. What I always loved about these appearances is that the audience could see the mystery guest sign his name. The show's mystery celebrities would often try to disguise their voices to confuse the panelists (Gypsy Rose Lee stuffed marbles in her mouth).

Thanks to YouTube, many of the classic "Mystery Guest" segments from the show are now available online. As viewers watch these appearances from a distance of nearly half a century, they offer a fascinating look into a world of entertainment and celebrity lifestyles that seems much smaller, tamer, and more intimate than today's relentless publicity machines and rabid paparazzi.

Opera Singers visit What's My Line?