Between Celtic and Graeco-Roman art there existed an irreconcilable antagonism. Celtic art, the art of pre-Roman Gaul, was essentially decorative and abstract, loving geometric motifs and the stylization of living forms for purposes of ornamentation; whereas Graeco-Roman art favoured naturalism and anthropomorphism. No real synthesis of these two opposed artistic doctrines was possible; so that Gallo-Roman art, the result of an attempt at an impossible synthesis, forced upon the Celtic artist by his Roman conqueror, is, judged by a purely aesthetic criterion, a very mediocre product. Its interest, therefore, is not primarily aesthetic, but historically its importance is paramount; for the extant sculptures, in all their diversity and extent, throw a flood of light on the religious cults, social customs, and economic conditions of Roman Gaul. Confining ourselves to Gallo-Roman religious sculpture, our object here is to give a general survey of the iconography of peculiarly Celtic deities which survived in the Roman province, as represented in sculptures of stone and bronze. Our concern, then, is not with Celtic religion as a whole, but only with its artistic aspect in the Roman era; but even so, literary and epigraphical evidence will frequently prove illuminating in the interpretation of the works of art. We must, clearly, exclude from our scope all purely Graeco-Roman divinities imported into Gaul, together with the Oriental and Egyptian deities of the second and third centuries a.d., and the later Christian monuments. Out of this sentina numinum, this kitchen-midden of all sorts of cults, we select for discussion here only the religious imagery of Celtic divinities which survived the Roman domination. But, before embarking on this venture, a brief sketch of the salient features of Celtic religion will be relevant.