[I]n their 1980 book, Metaphors We Live By,the linguist George Lakoff (at the University of California at Berkeley) and the philosopher Mark Johnson (now at the University of Oregon) revolutionized linguistics by showing that metaphor is actually a fundamental constituent of language. For example, they showed that in the seemingly literal statement “He’s out of sight,” the visual field is metaphorized as a container that holds things. The visual field isn’t really a container, of course; one simply sees objects or not. But the container metaphor is so ubiquitous that it wasn’t even recognized as a metaphor until Lakoff and Johnson pointed it out.
From such examples they argued that ordinary language is saturated with metaphors. Our eyes point to where we’re going, so we tend to speak of future time as being “ahead” of us. When things increase, they tend to go up relative to us, so we tend to speak of stocks “rising” instead of getting more expensive. “Our ordinary conceptual system is fundamentally metaphorical in nature,” they wrote.