Isaiah 41:18

I will open rivers - That is, I will cause rivers to flow (see the note at Isaiah 35:7). The allusion here is doubtless to the miraculous supply of water in the desert when the Israelites had come out of Egypt. God then supplied their needs; and in a similar manner he would always meet his people, and would supply their needs as if rivers of pure water were made to flow from dry and barren hills.

In high places - The word used here denotes properly barrenness or nakedness Job 33:21; and then a hill that is bare, or destitute of trees. It is applied usually to hills in a desert Jeremiah 3:2, Jeremiah 3:21; Jeremiah 4:11; Jeremiah 7:29; Jeremiah 14:6. Such hills, without trees, and in a dry and lonely desert, were of course usually without water. The idea is, that God would refresh them as if rivers were made to flow from such hills; and it may not improperly be regarded as a promise that God would meet and bless his people in situations, and from sources where they least expected refreshment and comfort.

And fountains in the midst of the valleys - (See Isaiah 30:25, note; Isaiah 35:6, note).

I will make the wilderness - (See the note at Isaiah 35:7).