Q. Why are candles lit on the eve of Shabbat?
A. Perhaps originally as a protest against the ancient, movable Babylonian Sabbath which was regarded as an unlucky and gloomy day. In contrast to this, it was customary in Jewish homes that the final preparation for the Sabbath was the light. To emphasise that the home should be bright on Shabbat, it was ordained that the kindling of the lights should be a religious ceremony and a b’rachah should be said.
The lights were also interpreted by some as commemorating the weekly refilling and rekindling the Menorah in the Temple.
Today of course the candles usher in and symbolise the joyous delight and cheerful serenity that prevades Shabbat. The two Sabbath lights recall the two versions of the Shabbat commandment: Zachor (Ex. 0:8), “Remember the Sabbath day”, and Shamor (Deut. 5:12), “Observe the Sabbath day”.