Although he considered himself a haberdasher, John Graunt is better known as the founder of demography, the statistical study of human populations. With no formal training in mathematics, Graunt's work added immeasurably to human knowledge and his method of record keeping, an unknown technique more than three hundred years ago, contains lessons to be followed today. His work influenced another noted pioneer in this field, Sir William Petty, as well as Edmond Halley, English astronomer and "discoverer" of the comet named for him.

Born in London, England, on April 24, 1620, to Henry, a draper, and Mary Graunt, John was the eldest in a large family, and he eventually took over his father's business, as "haberdasher of small wares," a profession he continued for most of his life. His business and home, however, were destroyed in the London fire of 1666. A prosperous merchant, Graunt was a respected London citizen, holding...