This was the first of these plans. It began as the convergence of several streams of thought. My topical indexes of the Bible and hymnals had grown to contain enough material for sequences larger than the traditional three or four songs. (For the flexibility to select songs for a smoothly flowing sequence, it seems to take about four times more candidates than are actually used.) I had generated a large list of metaphorical references to springs or rivers; and had identified many specific scriptural allusions in the hymns.
The July/August 1994 issue of Biblical Archaeology Review featured a fascinating and ground-breaking set of articles on the water supply of Jerusalem, showing its geographic and historical importance. I drew on this source for much of the historical background in the introduction. Virtually every phrase in the introduction relates to specific details in the selected scriptures and songs.
Another stream has been a linguistic principle concerning the fore-telling aspect of prophecy. Some of the vast confusion concerning "literal" or "figurative" language may be cleared up by recognizing that the "literal" meaning even of a prophetic word necessarily comes from the past, not the future. This is because the literal meaning of any word can only come from the experience of the community that uses it. A prediction for the future can only be expressed through words that already mean something to the hearers. It is often more informative, more understandable, and more valuable to keep this limitation explicit, saying in effect, "The coming event will be like what happened before (at such and such a place), only greater (or worse)." Many prophecies are built around this kind of insight, often appearing in the syntax of metaphor or simile. The likeness is often elaborated and emphasized with details taken, naturally enough, from historical particulars of the earlier events.
For example, the return from exile in Babylon is a new exodus; and the coming of the Messiah is a return from another kind of exile. The concept "Day of the Lord" is built on a series of historical events; but an event "Last Day of the Lord" cannot be assumed to be limited by these earlier events -- it might differ from them, or surpass them, in any number of particular details in ways not distinguishable by the choice of words describing it.
After studying this historical and geographic background, many details in the prophecies made sense: and thus, many hymns took on new significance. I need hardly emphasize the importance of these prophecies -- the prophets of ancient Israel and the hymnwriters of the church have filled our worship with them. I merely note that I, and those with whom I had studied in many places, had overlooked something important.
I mentioned in passing some of those allusions to the times when Moses struck the rock. They deserve mention because of their number, although they are typically obvious enough not to need explanation. This also serves as a reminder that not every metaphorical reference to a river flows from the same source. (The "Stygian river," or "river of death" of many songs alludes to yet another geographical locus, deriving meaning from the literary context of Greek mythology.)
Sometimes people carelessly or ignorantly suppose that every word or phrase has exactly one metaphorical meaning, and perhaps even try to imbue every single occurance of it with that one significance. Students who comprehend the depth of their own lack of understanding are perhaps even more likely to fall into this trap in desperation. But language does not and cannot work that way, as this plain counter-example shows.