He learned, indeed, that if one pressed the stirrups as the shoulders of the horse swung down and leaned a trifle forward when the shoulders rose again, the motion ceased to be jarring; for she was truly a matchless creature and gaited like one of those fabulous horses of old, sired by the swift western wind.  In a little time a certain pride went beating through the veins of the doctor, the air blew more deeply into his lungs, there was a different tang to the wind and a different feel to the sun—­a peculiar richness of yellow warmth.  And the small head of the horse and the short, sharp, pricking ears tossed continually; and now and then the mare threw her head a bit to one side and glanced back at him with what he felt to be a reassuring air.  Life and strength and speed were gripped between his knees—­he flashed a glance at the girl.

But she rode with face straightforward and there was that about her which made him turn his eyes suddenly away and look far off.  It was a jagged country, for in the brief rainy season there came sudden and terrific downpours which lashed away the soil and scoured the face of the underlying rock, and in a single day might cut a deep arroyo where before had been smooth plain.  This was the season of grass, but not the dark, rank green of rich soil and mild air—­it was a yellowish green, a colour at once tender and glowing.  It spread everywhere across the plains about Elkhead, broken here and there by the projecting boulders which flashed in the sun.  So a great battlefield might appear, pockmarked with shell-holes, and all the scars of war freshly cut upon its face.  And in truth the mountain desert was like an arena ready to stage a conflict—­a titanic arena with space for earth-giants to struggle—­and there in the distance were the spectator mountains.  High, lean-flanked mountains they were, not clad in forests, but rather bristling with a stubby growth of the few trees which might endure in precarious soil and bitter weather, but now they gathered the dignity of distance about them.  The grass of the foothills was a faint green mist about their feet, cloaks of exquisite blue hung around the upper masses, but their heads were naked to the pale skies.  And all day long, with deliberate alteration, the garb of the mountains changed.  When the sudden morning came they leaped naked upon the eye, and then withdrew, muffling themselves in browns and blues until at nightfall they covered themselves to the eyes in thickly sheeted purple—­Tyrian purple—­and prepared for sleep with their heads among the stars.

Something of all this came to Doctor Randall Byrne as he rode, for it seemed to him that there was a similarity between these mountains and the girl beside him.  She held that keen purity of the upper slopes under the sun, and though she had no artifice or careful wiles to make her strange, there was about her a natural dignity like the mystery of distance.  There was a rhythm, too, about that line of peaks against the