There are many introductions to „the Celts“ or to specific matters which may be labelled „Celtic“. Most of them, written by archaeologists and often superbly illustrated, have an archaeological bias concentrating on material culture. The present introduction, written by a linguist and philologist, rather stresses the non-material aspects, relying more on historical sources and, above all, on the authentic testimony of the literary tradition embodied in the extant insular Celtic languages.