Thus it appears that in many parts of Europe it has been customary to kindle fire by the friction of wood for the purpose of curing or preventing the spread of disease, particularly among cattle. The mode of striking a light by rubbing two dry sticks against each other is the one to which all over the world savages have most commonly resorted for the sake of providing themselves with fire;[739] and we can scarcely doubt that the practice of kindling the need-fire in this primitive fashion is merely a survival from the time when our savage forefathers lit all their fires in that way. Nothing is so conservative of old customs as religious or magical ritual, which invests these relics of the past with an atmosphere of mysterious virtue and sanctity. To the educated mind it seems obvious that a fire which a man kindles with the sweat of his brow by laboriously rubbing one stick against each other can possess neither more nor less virtue than one which he has struck in a moment by the friction of a lucifer match; but to the ignorant and superstitious this truth is far from apparent, and accordingly they take infinite pains to do in a roundabout way what they might have done directly with the greatest ease, and what, even when it is done, is of no use whatever for the purpose in hand. A vast proportion of the labour which mankind has expended throughout the ages has been no better spent; it has been like the stone of Sisyphus eternally rolled up hill only to revolve eternally down again, or like the water poured for ever by the Danaids into broken pitchers which it could never fill. [The belief that the need-fire cannot kindle if any other fire remains alight in the neighbourhood.]