Metaphor has long been thought to involve two things, frequently labeled domains—a target domain people are seeking to understand, and a source domain to help with that understanding. Whether the connection between these domains allows for one-way or two-way traffic, is a matter of much debate. And what those domains actually are, as some kind of conceptual structures, is also a slippery issue (Gibbs, 2017). But that metaphor involves two of these things, is a well-received idea. Moreover, recent research has noted that most forms of figurative language, including metaphor, also invoke exactly two of these “domains”, though they do different things with them than does metaphor. So two seems a magic number of sorts, in figurative language and metaphor (Colston, 2019). Why might this be? The idea suggested here is that it isn’t so much that metaphor just happens to involve two domains, but rather that cognition in general, involves representation (whether in an information processing, an embodied cognition, or in some other sense), of a single or multiple domains, but that once it moves from handling one domain to two, something very special is enabled. Having the neural machinery to hold one concept in mind, while invoking a second one, allows for a wide variety of cognitive processes, resembling and including metaphorical thought (and language). People can compare (which is bigger?), contrast (which is better?), substitute (a long stick STANDS FOR a long arm), as well as metaphorize (contentment IS warm sunshine). So such an ability seems to bridge the very earliest possibilities in thought about more than one thing at a time, all the way up to the most profound and meaningful poetic metaphors (Rasse, 2022).