Some measure of generality must be present in any high-class theorem, but too much tends inevitably to inspidity. ‘Everything is what it is, and not another thing’, and the differences between things are quite as interesting as their resemblances. We do not choose our friends because they embody all the pleasant qualities of humanity, but because they are the people they are. And so in mathematics; a property common to too many objects can hardly be very exciting, and mathematical ideas also become dim unless they have lenty of individuality.
–GH Hardy “A Mathematician’s Apology”