In the 1999 Galton Lecture for the annual conference of The Galton Institute, the author summarizes the main elements of Galtongenerals original and largely intuitive ideas, which still inspire mainstream scientific research on intelligence.

Acquisition of word meanings, or vocabulary, reflects general mental ability (psychometric g) more than than do most abilities measured in test batteries. Among diverse subtests, vocabulary is especially high on indices of genetic influences. Bloom's exposition of the psychological complexities of understanding words, involving the primacy of concepts, the theory of mind, and other processes, explains vocabulary's predominant g saturation.