This Parsha begins with a reference to the lighting of the Menorah in the Mishkan, which had to be done daily (שמות כ"ז:כ'-כ"א). The Posuk in Mishlei (ו':כ"ג) mentions the term "תורה אור," indicating that the Torah is like a light, or a fire. Like a flame, the Torah illuminates the proper path for the Jews, and without the Torah, our lives remain darkened. However, it is not sufficient for us to bask in the flames of Torah only in our homes. Rather, we must take the approach of Avraham Avinu, who spread the flames of the Torah to all the surrounding areas. In this sense, he acted like a candle, which can kindle other candles while continuing to burn brightly on its own; similarly, the light of the Torah never diminishes, no matter how many individuals benefit from its fire. The Gemara in Megillah (דף ט"ז:), commenting on the Posuk in Megillas Esther (ח':ט"ז) which states that the Jews had light, says that light is Torah, presumably because of the above reasons. Chazal also tell us that just as the light is superior to the darkness, so is the Torah superior to things of vanity.
The light of Torah shines, however, not only on intellectual achievement, but on all aspects of life which can benefit from it. The story is told about a woman who once appeared before the Taz, crying that her only son was about to die, the doctors having abandoned all hope for his survival. As a final desperate gesture, she came to the Taz, who suggested that the woman pray to Hashem. "But I have already prayed and I will continue to do so," she said, "can you offer a prayer?" The Taz became lost in deep thought. He lifted his face and said, "For two weeks I have been trying to figure out an answer to a Torah question. Now I will pray to Hashem that the merit of my struggle should serve as a blessing for your sick son. The prayer was fulfilled, and the son recovered due to the benefit of the Torah. We thus see how involvement in Torah can influence much beyond intellectual growth. Although the benefits are not usually as dramatic as in that story, the fact is that people involved in Torah are able to influence themselves and others in very significant ways because they can shape our society and the world in which we live by shining forth, just like a candle in the darkness.