By the 1860s, the term "science" (as meaning something distinct from "philosophy") entered the dictionary. Today the term "metaphysics" usually refers to discussion of aspects of reality which are beyond physics. Particularly among those seeking to be scientific, the term "metaphysics" can be pejorative to varying degrees. However, philosophers of science recognize that science is impossible without metaphysics. At the very least, before beginning empirical investigation, one needs an ontology. This is because categories are needed to sort observations into.