The botanist Carl von Linné, better known as Linnaeus, popularized this way of thinking about plants (as well as animals) in the eighteenth century. Nowadays, children take the idea for granted; they think the Taxonomy of plants and animals is just a tedious academic exercise. But back then, the idea extended the very way in which people could think about the world. For example, if I connect butterflies with insects, I establish a mental crutch that helps me *reuse* knowledge I already have about insects. Everything I know co be true of insects automatically applies to butterflies — six legs, egg-laying, metamorphose, breathe through holes in their bodies.… All I had to do was stipulate that a butterfly is a kind of insect (or say "inherits from" or "is a subclass of"). That's a lot of cognition to get free, or for the small price of stipulating an AKO relationship.
AKO – A-Kind-Of.