Billali--who, by the way, was none the worse for his immersion of the
day before--nodded his head sagely as he replied--

"Thou art right, my son. It is a channel cut out by those who were
before us in this place to carry away water. Of this I am sure: within
the rocky circle of the mountain whither we journey was once a great
lake. But those who were before us, by wonderful arts of which I
know naught, hewed a path for the water through the solid rock of the
mountain, piercing even to the bed of the lake. But first they cut the
channel that thou seest across the plain. Then, when at last the water
burst out, it rushed down the channel that had been made to receive it,
and crossed this plain till it reached the low land behind the rise,
and there, perchance, it made the swamp through which we have come. Then
when the lake was drained dry, the people whereof I speak built a mighty
city on its bed, whereof naught but ruins and the name of Kôr yet
remaineth, and from age to age hewed the caves and passages that thou
wilt see."

"It may be," I answered; "but if so, how is it that the lake does not
fill up again with the rains and the water of the springs?"

"Nay, my son, the people were a wise people, and they left a drain to
keep it clear. Seest thou the river to the right?" and he pointed to a
fair-sized stream that wound away across the plain, some four miles from
us. "That is the drain, and it comes out through the mountain wall where
this cutting goes in. At first, perhaps, the water ran down this canal,
but afterwards the people turned it, and used the cutting for a road."

"And is there then no other place where one may enter into the great