Next let me very briefly sum up what it is that Dr. Delitzsch has done—marshalling the evidence, beginning from the broad end and narrowing down till we arrive at the point.
(1) First, then, we are fixed by the narrative to some place between the Euphrates and the Tigris.
(2) We find in the ancient inscriptions of the chief city of this locality, constant allusions to a Garden, a primitive pair and a temptation: one of these almost exactly reproduces the Bible story; it is not of the earliest date and is a copy. But discovery is far from being exhausted; all that we know is consistent with the idea of an original story, gradually corrupted by the addition of legends, and introduction of mythological persons and heathen divinities. The true belief in one God, who made Himself known by voice or vision to His true worshippers, seems early to have been confined to a few of the Shemitic families, while the others "invented" gods of their own.
(3) We find that the region about Babylon itself was called Kár-dunishi—which easily recalls Kar or Gán-Eden. We also find the name (Tintira) applied, indicating a "grove" or "fountain" of life; in the locality where the direct legends most abound.
(4) We find from ancient authors that the district was one of rich verdure—a land of gardens and irrigation.
(5) We find that some way above Babylon about Accad, the level of the river bed Euphrates is so much higher than the valley of the Tigris eastward, that numerous streams flow off from it, which would serve admirably to irrigate a garden situated between the two, eastward of the Euphrates.
(6) We find that the Persian Gulf once extended more than one hundred miles farther inland than it does now. That there was no joint outflow of Tigris and Euphrates, but, though they did join their streams above, they parted again and had still separate mouths—of the Tigris branch one, of the Euphrates several.
(7) Lastly, Professor Delitzsch finds two channels which answer to Pison and Gihon.
(8) He proves these two to be the right ones by considering the countries which they "compass:" and actually finds the one that he supposes to be the "Gaihûn," called, in the cuneiform clay tablets, "Kahán or Gaghân-dé."
It is really only in (7) and (8) that there is any room for doubt and for further inquiry.