Nor was the keeping up of this fire a mere matter of unmeaning form, a simple custom to which no signification of any particular importance was attached; it was essentially connected with the people's most ancient and cherished religious beliefs. So serious a matter was it that even the particular kind of wood was specified. Virgil and Plutarch distinctly state that only certain trees ought to be used for such a purpose, and these were kept sacred and forbidden for other uses. The fire, according to Euripides and Ovid, must be kept pure--no polluted object might be cast into it, no offensive action might be performed in its presence. As we remark in another place, there was one day in the year (March 1st in Rome) when all fires and lights were put out--but immediately renewed with the observation of many rites. The strictest rules had to be attended to on these occasions; it was forbidden to renew the fire from any remaining spark of the old--indeed it was essential to thoroughly extinguish every spark of the previous flame--neither might a spark be struck from flint and steel; only by the sun's rays or by rubbing two pieces of wood together might the new fire be started into being, for the fire was regarded as the representative of the sun--the greatest of lights and fires, and as such was adored. Well it was not unreasonable or to be wondered at, that men, for want of better knowledge, should render divine honours to that from which they received such benefits; they saw the light and heat of the sun pouring down upon the earth and in conjunction with the rain and dew, softening its crust, swelling and fructifying its seed and bringing forth from it food and nourishment for man and beast. And so they prayed as we read in the Orphic hymns: "Render us always flourishing, always happy, O fire: thou who art eternal, beautiful, ever young; thou who nourishest, thou who art rich, receive favourably these our offerings, and in return give us happiness and sweet health." The fire seems to have been perpetually invoked; hardly a monument was made, hardly a household or business duty performed or engagement fulfilled, without a prayer to it; if a man left his home for a brief while, he worshipped the fire; when he returned, before he saluted his nearest relatives, the same duty was observed. Æschylus tells of Agamemnon returning from Troy, and instead of going to the temple and returning thanks to Jupiter, offering thanksgiving before the fire in his own house. Euripides, also, represents the dying Alcestis speaking to the fire: "Mistress, I go beneath the earth, and for the last time fall before thee, and address thee. Protect my infant children; give to my boy a tender wife, and to my daughter a noble husband. Let them not die, like their mother, before the time, but may they lead a long and happy life in their fatherland."