Question
Was there an eternal light in the Temple?
Answer
The westernmost of the lights in the menorah burned perpetually (Talmud Shabbat 22b). (The menorah stood against the south wall of the tabernacle, so the westernmost light was the one on the right end.) The Talmud says that the westernmost light burned perpetually to demonstrate that the Divine Presence dwelt in the Tabernacle. Aaron relit all the lights in the menorah every evening, but the westernmost light was the only one that was still burning when he refilled it with oil and trimmed its wick. The oil that Aaron put in the menorah was only enough to burn all night; the fact that the westernmost light lasted until the next night was miraculous.