Thus with the darkness grew his imaginative interpretation of the Desert.  Yet there was construction in it, a construction, moreover, that was not entirely his own.  Powers, he felt, were rising, stirring, wakening from sleep.  Behind the natural faces that he saw, these other things peered gravely at him as he passed.  They used, as it were, materials that lay ready to their hand.  Imagination furnished these hints of outline, yet the Powers themselves were real.  There was this amazing movement of the sand.  By no other manner could his mind have conceived of such a thing, nor dreamed of this simple, yet dreadful method of approach.

Approach! that was the word that first stood out and startled him.  There was approach; something was drawing nearer.  The Desert rose and walked beside him.  For not alone these ribs of gleaming limestone contributed towards the elemental visages, but the entire hills, of which they were an outcrop, ran to assist in the formation, and were a necessary part of them.  He was watched and stared at from behind, in front, on either side, and even from below.  The sand that swept him on, kept even pace with him.  It turned luminous too, with a patchwork of glimmering effect that was indescribably weird; lanterns glowed within its substance, and by their light he stumbled on, glad of the Arab boy he would presently meet at the appointed place.

The last torch of the sunset had flickered out, melting into the wilderness, when, suddenly opening at his feet, gaped the deep, wide gully known as Wadi Hof.  Its curve swept past him.

This first impression came upon him with a certain violence:  that the desolate valley rushed.  He saw but a section of its curve and sweep, but through its entire length of several miles the Wadi fled away.  The moon whitened it like snow, piling black shadows very close against the cliffs.  In the flood of moonlight it went rushing past.  It was emptying itself.

For a moment the stream of movement seemed to pause and look up into his face, then instantly went on again upon its swift career.  It was like the procession of a river to the sea.  The valley emptied itself to make way for what was coming.  The approach, moreover, had already begun.

Conscious that he was trembling, he stood and gazed into the depths, seeking to steady his mind by the repetition of the little formula he had used before.  He said it half aloud.  But, while he did so, his heart whispered quite other things.  Thoughts the woman and the man had sown rose up in a flock and fell upon him like a storm of sand.  Their impetus drove off all support of ordinary ideas.  They shook him where he stood, staring down into this river of strange invisible movement that was hundreds of feet in depth and a quarter of a mile across.

He sought to realise himself as he actually was to-day—­mere visitor to Helouan, tempted into this wild adventure with two strangers.  But in vain.  That seemed a dream, unreal, a transient detail picked out from the enormous Past that now engulfed him, heart and mind and soul. This was the reality.