Our Gemara on Amud Beis quotes a verse in

Mishle (6:23)

כִּ֤י נֵ֣ר מִ֭צְוָה וְת֣וֹרָה א֑וֹר וְדֶ֥רֶךְ חַ֝יִּ֗ים תּוֹכְח֥וֹת מוּסָֽר׃

⁦For the commandment is a lamp, The teaching is a light, And the way to life is the rebuke that disciplines.

In order to understand this metaphor properly, it is important to know biblical Hebrew. A ner is not a candle. Candles were not invented, or at least not used popularly, until the middle ages. Ner means lamp.

Now when you use a lamp, you’ll notice that it has two parts. There is the base of the lamp that stores the fuel such as oil, and then there is the wick. The verse is saying that the lamp, i.e. the storage container that holds the fuel, is the mitzvah. While the light, that is less physical manifestation but ultimate vital product, is the light.

Now we can understand that this metaphor is quite deliberate. The Torah, that is The light and desired effect, cannot exist independently without the physical fuel and the base, that is the lamp. Therefore, we perform the mitzvos as fuel in order to achieve the intangible state of enlightenment, known as the light of the Torah. 

This pattern in nature and life it’s important to recognize. Many times the desired effect is less tangible then the process to achieve it. We must engage often in physical efforts to help us achieve spiritual or emotional ends. For more on this see Iggeres HaGrah (8), Nefesh HaChayyim (4:29), and Tiferes Yisrael (14)