For some, lighting Shabbat candles is a reminder of their obligations to God, since the berakhah speaks of the commandment to kindle lights for Shabbat. For others, it is a symbol of the light of God's presence in our world, perhaps an association with the Ner Tamid (eternal light). For still others, Shabbat candles represent the warmth of the Jewish family.
The reason we light Shabbat candles has an interesting history behind it. In fact, there is no commandment in the Torah to light candles, despite the fact that the berakhah we says includes the words "asher kidshanu b'mitzvotav v'tzivanu le-had-lik ner shel Shabbat" (who has made us holy with commandments and has commanded us to light the Shabbat candles). The tradition of lighting Shabbat candles derives from a much later period in our history when there were Jewish communities scattered throughout the near east and Mediterranean basin, all of whom turned for guidance to the great academies in Babylonia, which were the center of Jewish learning in the world. The Karaites (called Kara'im or B'nei Mikra in Hebrew) are a sect of Jews who traces their beginnings to the Sadducees, but historians place their beginnings in the eighth century CE. The most famous Karaite leader of the Middle Ages was Anan ben-David (ninth century CE), the formal founder of the sect, a member of the exilarch family. Karaites denied the validity of the talmudic-rabbinic tradition, though Anan ben-David wrote his own treatise --Book of Commandments (of which fragments survive) -- which functioned as a single-source compendium of extra-biblical law for his community. Early Karaite leaders taught that the 39 types of work proscribed on Shabbat were to be extended to include any action not necessary or integral to the Shabbat worship service, nourishment of the family on Shabbat, or satisfaction of basic human needs. Hence, they prohibited the kindling of lights on the even of Shabbat and their use throughout Shabbat. rabbinic allowed permitted Jews to keep fires lit prior to sundown Friday evening to stay light, and additional fuel added to keep the home warm and light throughout Shabbat. The Karaites ruled, however, that not only could one not kindle lights on Friday evening, but all fires burning must be extinguished prior to sundown. As a result, their sabbaths were often dark, cold, and joyless, in the minds of the rabbinites. The rabbis, in order to make their point clearly, and to solidify the authority of rabbinic law throughout the Jewish community, instituted the recitation of a berakhah when lighting Shabbat candles, thus implying that it is a commandment with the force of Torah behind it. Menachem B. Joseph Bashyazi, a Karaite scholar and leader, first permitted the kindling of Shabbat around 1440 CE, after which the Karaites of Turkey, Crimea, Poland, and Lithuania began to light Shabbat candles. However, the Karaites of Egypt, Syria, and Eretz Yisrael continued to refrain from the practice.