I'm afraid that this line often brings to my mind a scene from the Sound of Muic,where the Reverend Mother quotes this line from Psalm 121 to urge the Von Trapp family to flee over the mountains to safety, then bursts into her grand aria, "Climb Every Mountain." So today, to clear my mind of this silliness befor its time for Evening Prayer, I turned to the commentary that our good Pope Benedict has done on this psalm.
He tells us that there are two completely different ways that scholars have interpreted this line. Psalm 121 is one of several psalms known as "songs of ascent", sung by pilgrims as they approach Jerusalem and look forward to worshipping in the Temple. So one might lift one's eyes to the holy mountain that is crowned by the holy city, and recall with gratitude that God helps his faithful chidren.
On the other hand,in another interpretation, mountains "conjure up images of idolatrous shrines in the so-clled 'high places', which are frequently condened in the Old Testament. (cf. 1 Kings 3:2, 2 Kings 18:4)"
In this case,Pope Benedict says, the pilgrim heading to Jerusalem glances at the mountains, recalls the presence of these pagan shrines, and feels tempted to visit them, given the historical proclivity of the Israelites to fall into idol worship. But then, after asking himself "from where shall come my help?" He resists temptation and sides with the Lord, "who made heaven and earth."
Two very different ways of looking at the identical verse.
The Pope goes on to explain the remainder of the psalm. Highlights of this teaching for me included bringing up the image of God as "your guard and your shade". We are mostly accustomed to images of ight and of the sun to help us think about God's glory and power to enlighten our minds. I enjoyed this contrast, recalling how in dry climates, such as Southern California where I once lived, stepping into the shade on a hot day made a startling difference. It was almost as refreshing as walking into an air-conditioned building, unlike my current northeast home where the humidity does not respect these sun/shade boundaries. Light speaks of God's glory and wisdom, but shade speaks of his protection and care for us.
By day the sun shall not smite you nor the moon by night. It's easy to realize that in the deserts of Israel the sun could kill you if you stay out in it at midday. Pope Benedict reminds us that people also used to believe that the rays of the moon could cause fever, blindness, or madness. (There is still a common folk belief to this day that suicides and mental health crises shoot up when the moon is full.) I'm glad that today we can enjoy the moon and its light as a thing of beauty.
You can read the whole commentary here.