Numbers 8:2

Speak unto Aaron and say unto him, When thou lightest the lamps, apparently the chief daily function of the high priest in those days, and a very important part of the officiating priest's work at a later period, the seven lamps shall give light over against the candlestick. Cf Exodus 25:37. The lamps were to be placed in their sockets on the candlestick in such a manner as to throw their light toward the front, thereby illuminating the Holy Place. This custom has a very definite significance in this connection, for Israel was at all times to be such a people before the Lord as to let its light shine in the darkness of this world.