The present generation can hardly understand what a new field Galton broke. Even Darwin had supposed that men do not differ very much in intellectual endowment, and that their differences in achievement are principally the result of differences in zeal and industry. Galton's articles, whose thesis was that better men could be bred by conscious selection, attracted much attention from the scientific world and were expanded in 1869 in his book Hereditary Genius.
This was an elaborate and painstaking study of the biographies of 977 men who would rank, according to Galton's estimate, as about 1 to 4,000 of the general population, in respect to achievement. The number of families found to contain more than one eminent man was 300, divided as follows: Judges, 85; Statesmen, 39; Commanders, 27; Literary, 33; Scientific, 43; Poets, 20; Artists, 28; Divines, 25. The close groupings of the interrelated eminence led to the conclusion that heredity plays a very important part in achievement. The greater success of real sons of great men as compared with adopted sons of great men likewise indicated, he thought, that success is due to actual biological heredity rather than to the good opportunities afforded the scion of the illustrious family. Galton's conclusion was that by selecting from strains that produced eminence, a superior human stock could be bred.
In 1874 he published a similar study of the heredity of 180 eminent English scientists, reëmphasizing the claims of nature over nurture, to use his familiar antithesis. In 1883 he published "Inquiries into the Human Faculty and Its Development," a collection of evolutionary and anthropometric essays where the word Eugenics was first used in a new exposition of the author's views. "Natural Inheritance" appeared in 1889, being the essence of various memoirs published since "Hereditary Genius," dealing with the general biological principles underlying the study of heredity and continuing the study of resemblances between individuals in respect to stature, eye color, artistic faculty and morbid conditions.