Under Roman influence the days of the week received Latin names derived from the planetary system, all of which except Sunday (_Dies Solis_ which became _Dies Dominica_) continued to be used by our lawyers until English took the place of Latin in the courts of record. In Cornwall, notwithstanding the Saxon invasion, the Latin names were retained until Cornish ceased to be a spoken and written language. Thus Sunday, _Dies Solis_ became _Dê Zil_, _Zil_ being the Cornish derivative of Sol and not a variant of the Cornish word Houl.[25] Until the Roman occupation the Celts reckoned time by nights, not days. Thus the first night (of the week if they had weeks) was the sixth night after new moon, that is when the moon was on the point of becoming half-full. Their year, therefore, consisted of thirteen months. The Celtic mind appears to have revelled in the realm of mystery. The practice of magic; the prevalence of human sacrifice; the numerous local divinities, with strange names preserved to us only in the dedications of their shrines, whose attributes and powers remain unknown; the hidden virtues of the mistletoe and the selago; above all, the secrets of the Celtic priesthood—the Druids—suggest, but unfortunately only suggest, a religious differentiation which carries us back to a period more remote than that of any religious system with which we are familiar. Professor Sir John Rhys has attempted to show that Druidism was a pre-Celtic survival, the religious system, in short, of some race which preceded the Celts in Britain, and his judgment would doubtless have been accepted had there not been good evidence to show that the system was not peculiar to Britain but to the Celts themselves. It prevailed among the continental Celts just as it prevailed among those of Britain and Ireland. On the other hand, its affinities with classical mythology are not sufficiently pronounced at the time when it is first encountered to indicate an Ægean origin. When the original home of the Celt has been determined it may be possible to discover the home of his religion.