Thou shalt command. Compare Exodus 25:6, where the general command had been given. Here certain additions are made as to the quality of the oil which was to be brought. The oil was to be pure olive oil beaten that is to say, it was to be olive oil purified from any admixture of that watery juice which the Romans called amurca; and it was to be of the kind which is obtained by mere beating or pounding in a mortar, and not by crushing in a mill.
Oil of this kind, which is usually made from the unripe fruit, is reckoned much the best; it is clear and colourless, and gives a bright pure light with little smoke. To cause the lamp to burn always.
It has been supposed from this expression that the lamp must have been kept constantly burning both day and night; and Josephus declares that this was actually so, at least with three out of the seven lights (Ant.
Jud. 3.7, 7). But there are several places m Scripture which state, or imply, the contrary. (See especially Exodus 30:8; and 1 Samuel 3:3.) It seems to have been the duty of the high-priest to light the lamps every evening, and to give them a sufficient supply of oil to last till daybreak, at which time "the lamp of God went out" (1 Samuel l.
s.c.) The supposition that "one light at least was always burning" (Kalisch), because no daylight could penetrate into the structure through the fourfold covering, ignores the fact that light would enter through the single curtain at the entrance, as well as the probability that some portion of that curtain may generally have been looped up.
If we regard the lamp as extinguished during the daytime, we must understand "always" here to mean "regularly every night."