The author of the _De imagine mundi_, borrowing from Isidore,[955] makes a qualitative subdivision.[956] Land, he says, may be grouped under six different heads, _terra_ being the name applied to the entire element of earth. The six kinds of _terra_ are: (1) _tellus_, fertile; (2) _humus_, infertile, because of an excess of moisture; (3) _arida_, waterless, like Libya, dried up by the sun; (4) _sicca_, rather less dry than _arida_, but where, nevertheless, all precipitation quickly disappears, as in Judea; (5) _solum_, so called from its solidity, as mountainous land (_a soliditate ut sunt montana_); and, finally (6) _ops_, or wealthy land, like that of India, where gold and gems abound.[957] In addition to such variations in the character of the lands, it was a common view that certain localities are by nature either peculiarly noxious or else peculiarly free from poisons. Gervase of Tilbury notes[958] an area near Pozzuoli which resembled a dried-up swamp but proved fatal to all animals venturing upon it. Elsewhere[959] he repeats, in connection with the tree of life spoken of by Alexander in his supposed letter to Aristotle, a widespread tradition of a land where no man could die even though he were decrepit with old age and might wish for relief from the cares of this world.[960] The _Image du monde_[961] attributes a similar quality to an island in the northern seas. When the inhabitants wished to die they had themselves taken to Tylle (Thule), where they might expire in peace. Giraldus Cambrensis describes[962] such an island in a lake in Ireland, as well as an island where no females could live. GIRALDUS CAMBRENSIS’ COMPARISON OF EAST AND WEST