Frank J. Wilstach, comp. A Dictionary of Similes. 1916.
Mirth
Mirth is like a flash of lightning that breaks through a gloom of clouds and glitters for a moment. Cheerfulness keeps up a daylight in the mind, filling it with a steady and perpetual serenity.
—Dr. Samuel Johnson
Mirth, like light, will all too often take its birth mid darkness and decay.
—Letitia Elizabeth Landon