An individual who is puzzled by an unfamiliar situation may try to explain it metaphorically, linking the new situation with one that is more familiar. Communication of ideas is facilitated by figurative thinking, in science as in poetry. However, metaphor has served other, more significant functions in science: it has helped generate theory, whose structure and origins may then be illuminated by root-metaphor analysis. The history of psychological theory and of science generally is full of examples of metaphoric thinking: Locke's tabula rasa, the mechanical psychologies of Hobbes and Hartley, and Lorenz' imprinting, to name a few. Many psychologists disparage metaphoric thinking as primitive or unscientific, and clearly it has its hazards and limitations. But properly used, the author of the present paper contends, it has a legitimate place in the development of theory, and undue caution may, in fact, hinder the free exploration of underdeveloped areas of knowledge. (Harvey Nash)