Why bless on Shabbat candles?

Shalom and thank you for your question! You are correct in your premise that lighting Shabbat candles is a different category of mitzvah than mitzvot that are specifically mentioned in the Torah, since it is a Rabbinic mitzvah. That is not a reason however,  not to make a blessing on it. It belongs to a special category called the Seven Rabbinic Mitzvot, which are: Reciting the Hallel prayer, making blessings, ritual hand-washing, the Shabbat Eiruv, lighting Shabbat candles, celebrating Purim – specifically through reading the Megilla,  and celebrating Chanukah including lighting the Chanukah candles.

These Rabbinic mitzvot come to strengthen the performance of the mitzvot that are enumerated in the Torah, or to commemorate events that were crucial to the spiritual development of the Jewish people. You may ask, how do the Rabbis have the authority to add mitzvot? We are actually taught not to add or detract from the Torah. So how does this work?

First we have to understand that the Five Books of Moses- the Chumash, the books of the Prophets and other books that compromise the Jewish Bible, are only one part of the Torah. They are called the Written Law,  because they were written down and passed on through the generations in written form. The Oral law was also received at Sinai and handed down through the generations, but it was taught orally and only written down when it was feared that it would otherwise be lost. Why do we need the Oral law? In Deuteronomy 6:8 it says for example “And they shall be for a sign between your eyes…” which we would not understand how to put in to practice without the Oral law. Jews in various far-flung corners of the earth have always, throughout the generations, performed this mitzvah by donning Tefillin which are certain portions of the Torah written by a scribe on pieces of parchment, and inserted into black leather boxes which are tied on the head and the arm with black leather straps. Without the Oral Torah we would not know this. The Rabbinic mitzvot were enacted by special judicial courts which also issued decrees whose purpose was to support the performance of the mitzvot of the Torah. The Talmud tractate Sanhedrin 88b teaches us that we are to be strict with the words of the Sages even more than with the words of the Torah! “For their words are more precious to G-d than His own – just as the words of a wise child may be more precious to a parent or teacher than his or her own.” In Deuteronomy 17:11 it states: “According to the law they instruct you and according the judgement they tell you shall you do, you shall not digress from the word (they tell you) either right or left.” This indicates that we must abide by the rulings of the great Rabbinical courts,  the Sanhedrin.

The prophet Isaiah (53:13) instructs us to “call the Sabbath day a delight and G-d’s holy day honored.” Lighting Shabbat candles is an enactment which helps us put that idea into practice, specifically the Sages say that we should not have to stumble in the dark. Some people,  such as the Karaite sect, thought that since the Torah states that “You shall not burn fire in your dwelling places (on the Sabbath)” (Exodus 35:3), we must sit in the dark in the Sabbath. The Oral law comes to teach us that this not so. The Sages enacted the mitzvah of candle-lighting to make sure that Jewish homes would be lit up with a physical light which is also a spiritual light. It is meant to help us not stumble physically OR spiritually.

We hope this has been helpful and wish you a sweet and blessed Jewish New Year!