The fall of the Celtic state worship began earlier in Britain than in her sister island. Neither was it Christianity that struck the first blow, but the rough humanity and stern justice of the Romans. That people was more tolerant, perhaps, than any the world has ever known towards the religions of others, and gladly welcomed the Celtic gods—as gods—into its own diverse Pantheon. A friendly Gaulish or British divinity might at any time be granted the so-to-speak divine Roman citizenship, and be assimilated to Jupiter, to Mars, to Apollo, or to any other properly accredited deity whom the Romans deemed him to resemble. It was not against the god, but against his worship at the hands of his priests, that Roman law struck. The colossal human sacrifices of the druids horrified even a people who were far from squeamish about a little bloodshed. They themselves had abolished such practices by a decree of the senate before Caesar first invaded Britain,[558] and could not therefore permit within their empire a cult which slaughtered men in order to draw omens from their death-agonies.[559] Druidism was first required to be renounced by those who claimed Roman citizenship; then it was vigorously put down among the less civilized tribes. Tacitus tells us how the Island of Mona (Anglesey)—the great stronghold of druidism—was attacked, its sacred groves cut down, its altars laid level, and its priests put to the sword.[560] Pliny, recording how the Emperor Tiberius had “suppressed the druids”, congratulates his fellow-countrymen on having put an end, wherever their dominion extended, to the monstrous customs inspired by the doctrine that the gods could take pleasure in murder and cannibalism.[561] The practice of druidism, with its attendant barbarities, abolished in Britain wherever the long Roman arm could reach to strike, took refuge beyond the Northern Wall, among the savage Caledonian tribes who had not yet submitted to the invader’s yoke. Naturally, too, it remained untouched in Ireland. But before the Romans left Britain, it had been extirpated everywhere, except among “the Picts and Scots”.