How far we have come! Since the mid-twentieth century, philosophers have accepted that metaphor and analogy permeate all discourse, are fundamental to human thought and provide a basis for mental leaps (sse Black, 1962; Goswami, 1992; Johnson, 1981; Lakoff & Johnson 1980; Schon, 1983). Similarly, the potential contribution of metaphor and analogy to cognitive learning (e.g., in schools) has attracted the attention of the science education research community (Genter & Stevens, 1983). The first important revelation is that metaphor is not merely a linguistic phenomenon. It also is a fundamental principle of thought and action (see Johnson, 1981). The second revelation is that analogies are more specific than metaphors and, despite their wide use in everyday communication and reasoning, their use in teaching is often problematic because the applicability of specific analogies is not negotiated with students. Consequently, researchers have been and are interested in the form and function of analogy and metaphor in learning and teaching science.