Context: The idea that physical decline is not dependent on chronology has frequently been expressed. One version was the punning comment: "Whether life is worth living or not depends on the liver." In 1806, Dr. Pierre J. G. Cabanis (1757–1808), the French physician and philosopher, published the medical epigram: "A man is as old as his arteries." The American man of letters George William Curtis (1824–1892) wrote in Prue and I (1857): "Age . . . is a matter of feelings, not of years." However, it remained for a British teacher of mathematics to figure out the best formula for determining the age of both men and women. As a pastime, Mortimer Collins wrote and published a quantity of light verse which appeared in magazines, and the works were published in four volumes: Idylls and Rhymes (1855), Summer Songs (1860), The Inn of Strange Meetings (1870) and a posthumous Selections from the Poetical Works of Mortimer Collins (1886), edited by Collins's wife's cousin, F. Percy Cotton, who provided musical settings for a number of them. Collins was also editor of a satirical poem, The British Birds, a Communication from the Ghost of Aristophanes (1872), and several novels, including Sweet Anne Page (1868). All of them might have been forgotten along with the name of the author, in the passing of time, had Collins not written one brief poem known both by its mathematical-sounding title, The Unknown Quantity, and by the simpler How Old Are You?
O wherefore our age be revealing?Leave that to the registry books!A man is as old as he's feeling,A woman as old as she looks.