Essentialism is the idea that the world is divided into real, discontinuous and immutable "kinds". This idea is the basis for most typological constructions particularly of stone artefacts where essential forms are often thought of as "mental templates" or combinations of traits that are favoured by the maker. Variation in artifact form and attributes is seen as a consequence of the imperfect realization of the template and is usually attributed to differences in raw material properties or individuals' technical competences.