Helen Keller? Walt Whitman? Charles Swain? Celia Burleigh? Lydia G. Worth? Edmund Cooke? M. B. Whitman? Maori Proverb? Question for Quote Investigator: A popular metaphorical framework equates sunlight to positive situations and shadow to unfavorable conditions. Here are two instances of an adage about maintaining an optimistic perspective: This notion has been credited to prominent …