Lakoff and Johnson use the word metaphor in two different ways. I prefer two different terms.
Sometimes when they say "metaphor" they mean a single figure of speech like "Our love has gone off the rails," analogizing a troubled love affair to a train having trouble on the tracks.
However, that sentence can be considered an instance of a more general metaphor, like LOVE IS A JOURNEY." Typographically, such general statements are written in small caps 
, so they don't appear to be SHOUTING AT YOU.
I can't use small caps here. In any case, I have a sneaking notion that it's helpful to be clear about the distinction between a general claim and its concrete instances.