The author of the _De imagine mundi_,[1230] copying from Isidore,[1231] makes the four rivers disappear into the ground, whence they spring forth in lands far distant; and some of the maps of our period represent all four rivers as rising from a central source within the Garden and vanishing into the earth at its walls or not far beyond. The Psalter map,[1232] on the other hand, shows no less than five rivers issuing from an aperture leading out of Paradise and spreading out like a fan over the interior of Asia. Abelard[1233] explains carefully that if we interpret the Bible correctly there can be but one river within Paradise, that this divides into four outside of the Garden, and that the names given to each of the four are applied to those parts only “which flow from their sources to the sea.” We may assume that he refers here to the portions of the rivers between points where they issue from their subterranean passages and their mouths. Some writers would seem to imply, Abelard continues, that we cannot take literally the words of the Bible because the sources of some of the four streams are known and those of others are not. But, he asks, may not those streams, whose sources are supposedly known, in reality arise elsewhere far away and pass through numerous countries before issuing forth to the knowledge of mankind? There is no question but that this is the case with many streams, as is shown, he adds, by the statement in Boethius’ _De consolatione philosophiae_ (a famous work of the sixth century much read throughout the Middle Ages) that “the Tigris and the Euphrates spring from one source.” One version of the legend of Prester John informs us that the four rivers of Paradise all arise in a spring in the mountains of India and water the two Indias.[1234] Like most rivers of Prester John’s realm, they give forth quantities of gold and precious stones at regular intervals three times a year. Discussion of the individual characteristics of each of the four rivers falls more logically with the treatment of the ideas concerning the countries through which they flow and will be reserved until later. In most of the geographical works of our period, however, the rivers receive special consideration immediately after the remarks on Paradise and before the description of the regions of Asia. Their unusual origin and character, as described in Scripture, entitled them to particular distinction: they were holy streams to Jew and Christian alike. It is, then, a peculiarly eloquent commentary on the paganism of Bernard Sylvester to find that he mentions and describes the Euphrates, Tigris, and Nile in his _De mundi universitate_[1235] without referring to Paradise in connection with any of these three streams. To his thinking they would seem to have occupied no higher or holier place among streams than Tiber, Rhone, or Seine. _ASIA_