When thou lightest the lamps. The command to light the lamps had been given generally ("they shall light the lamps thereof") in Exodus 25:37, and the care of them had been specially confided to Aaron and his sons ("from evening to morning") in Exodus 27:21.
The actual lighting of the lamps for the first time by Moses is recorded in Exodus 40:25. In the face of these passages it is incredible that the lamps had not been regularly lighted by Aaron for more than a month before the offering of the princes.
The seven lamps shall give light over against the candlestick. It is somewhat uncertain what this expression, here repeated from Exodus 25:37, means. The Targums give no explanation of it; the Septuagint merely renders verbally, κατὰ πρόσωπον τῆς λυχνίας φωτιοῦσιν; the Jewish expositors seem to have thought that the light was to be thrown inward towards the central shaft; most modern commentators, with more probability, understand it to mean that the lamps were to be so placed as to throw their light across the tabernacle towards the north side.