A metaphor is an imaginative way of describing something by referring to something else which is the same in a particular way. It is a rhetorical device as well as a way of thinking. In The Great Didactic, John Amos Comenius used altogether 317 metaphors. The source domains of these metaphors can be categorized into three types, namely, natural things /phenomena, things in human society, human beings, and their behavior /actions. Their target domains are mainly about the aims /functions of education, school, teacher, student, and teaching. Comenius' metaphors are mostly conceptual ones, used in a wide range of contexts systematically. For educational researchers in modern times, metaphors remain a useful means to explain, illustrate, and spread their ideas. In fact, combining metaphors with deductive reasoning and empirical induction will help promote both the diversity and insightfulness of educational research, leading to fruitful results in educational theory innovation.