St Augustine saw "the mountains of Israel" as the Holy Scriptures: and he points us to run and rest and feed thereon. This is both a description and an example of the spiritual sense of reading Scripture:
"It was God who brought forth the mountains of Israel, that is to say, the authors of the divine Scriptures. Feed there that you may feed in safety. Whatever you hear from that source, you should savor. Whatever is foreign to it, reject. Hear the voice of the shepherd, lest you wander about in the mist. Gather at the mountains of holy Scripture. There, are the things that will delight your hearts; there , you will find nothing poisonous, nothing hostile; there, the pastures are most plentiful. There, you will be healthy sheep; you will feed safely on the mountains of Israel.
"From the mountains which we have shown you, there have issued the streams of the gospel message, because their voice has gone forth into the whole world, and every habitable place has become pleasant and fertile for the grazing sheep.
"In good pastures and on the high mountains of Israel, I shall feed them. And their grazing ground shall be there, that is, the place where they will say: 'I am happy.'"
--from today's Office of Readings