Authors:

The critic's symbol should be the tumble-bug: he deposits his egg in somebody else's dung, otherwise he could not hatch it.

Mark Twain (2014). “Mark Twain on Common Sense: Timeless Advice and Words of Wisdom from America's Most-Revered Humorist”, p.53, Skyhorse Publishing, Inc.
The critic's symbol should be the tumble-bug: he deposits his egg in somebody else's dung, otherwise he could not hatch it.