The reference to Ephraim in vv. 9-11 is not to be taken as alluding to any cowardly retreat from actual battle. Ver. 9 seems to be a purely figurative way of expressing what is put without a metaphor in the two following verses. Ephraim's revolt from God's covenant was like the conduct of soldiers, well armed and refusing to charge the foe. The better their weapons, the greater the cowardice and ignominy of the recreants. So the faithlessness of Ephraim was made darker in criminality by its knowledge of God and experience of His mercy. These should have knit the tribe to Him. A general truth of wide application is implied--that the measure of capacity is the measure of obligation. Guilt increases with endowment, if the latter is misused. A poor soldier, with no weapon but a sling or a stick, might sooner be excused for flight than a fully armed archer. The mention of Ephraim as prominent in faithlessness may be an allusion to the separation of the kingdoms. That allusion has been denied on the ground that it is the wilderness history which is here before the psalmist's mind. But the historical retrospect does not begin till ver. 12, and this introduction may well deal with an event later than those detailed in the following verses. Whether the revolt of the Ten Tribes is here in view or not, the psalmist sees that the wayward and powerful tribe of Ephraim had been a centre of religious disaffection, and there is no reason why his view should not be believed, or should be supposed to be due to mere prejudiced hostility. The historical details begin with ver. 12, but, as has been noticed above, the psalmist seems to change his intention of first narrating the wonders in Egypt, and passes on to dilate on the wilderness history. "The field of Zoan" is the territory of the famous Egyptian city of Tzan, and seems equivalent to the Land of Goshen. The wonders enumerated are the familiar ones of the passage of the Red Sea, the guidance by the pillar of cloud and fire, and the miraculous supply of water from the rock. In vv. 15, 16, the poet brings together the two instances of such supply, which were separated from each other by the forty years of wandering, the first having occurred at Horeb in the first year, and the second at Kadesh in the last year. The two words "rocks," in ver. 15, and "cliff," in ver. 16, are taken from the two narratives of these miracles, in Exod. xvii. and Numb. xx.