By an essay of Freeman Dyson entitled Frogs and Birds (http://www.pims.math.ca/scientific/scientific-lecture/ams-einstein-public-lecture-freeman-dyson-birds-and-frogs
), which was written for his planned Einstein Public Lecture. In it, he divides mathematicians (but I think it belongs not only mathematicians but all areas of science) up into two species: birds, who “fly high in the air and survey broad vistas” (i.e. seek abstraction, unification and generalization), and frogs, who “see only the flowers that grow nearby” (i.e. study the details of specific examples).