John Calvin Commentary Numbers 8:2

"Speak unto Aaron, and say unto him, When thou lightest the lamps, the seven lamps shall give light in front of the candlestick." — Numbers 8:2 (ASV)

When you light the lamps. This precept, like many others, is not inserted in its proper place.

Moses again declares what the use of the candlestick was, and how the lamps should be arranged, so that their light might be spread through the sanctuary, and that the brightness of the gold might shine opposite them. For this was the reason why God would have the lamps lighted against the face of, or opposite to, the candlestick, that the very stand of the light might retain its beauty.

Moreover, it is expressly stated that Aaron obeyed God’s command, as if it were no insignificant matter, as he had received it from Moses. To this also refers what immediately follows, that it was made according to the pattern which Moses had seen in the mount.

And this was, as I have explained before, that God is the Father of lights, who illuminates His Church by His Spirit, so that it may not wander in darkness. And so, while darkness covers the whole earth, He is an everlasting light to believers instead of the sun and moon, as Isaiah 60:19 says.