The problem with clichés is not that they contain false ideas, but rather that they are superficial articulations of very good ones. The sun is often on fire at sunset and the moon discreet, but if we keep saying this every time we encounter a sun or a moon, we will end up believing that this is the last rather than the first word to be said on the subject. Clichés are detrimental insofar as they inspire us to believe that they adequately describe a situation while merely grazing its surface. And if this matters, it is because the way we speak is ultimately linked to the way we feel, because how we describe the world must at some level reflect how we first experience it.
Alain de Botton. Wehr in the World: The problem with clichés.