Already some notion of preconception has possessed the observer. It could not have been chance which set off the filmy Bridal Veil against El Capitan's bulk; which designed the Gothic climax of Sentinel Rock; which wondrously proportioned the consecutive masses of the Three Brothers; which made El Capitan, now looked back upon against a new background, a new and appropriate creation, a thing of brilliance and beauty instead of bulk, mighty of mass, powerful in shape and poise, yet mysteriously delicate and unreal. As we pass on with rapidly increasing excitement to the supreme climax at the Valley's head, where gather together Glacier Point, Yosemite Falls of unbelievable height and graciousness, the Royal Arches, manifestly a carving, the gulf-like entrances of Tenaya and the Merced Canyons, and above all, and pervading all, the distinguished mysterious personality of Half Dome, presiding priest of this Cathedral of Beauty, again there steals over us the uneasy suspicion of supreme design. How could Nature have happened upon the perfect composition, the flawless technique, the divine inspiration of this masterpiece of more than human art? Is it not, in fact, the master temple of the Master Architect? [Illustration: _From a photograph by J.T. Boysen_ EL CAPITAN, SURVIVOR OF THE GLACIERS Looking eastward up the Yosemite Valley, Half Dome is seen on the right horizon] To appreciate the Valley we must consider certain details. It is eight miles long, and from half a mile to a mile wide. Once prehistoric Lake Yosemite, its floor is as level as a ball field, and except for occasional meadows, grandly forested. The sinuous Merced is forested to its edges in its upper reaches, but lower down occasionally wanders through broad, blooming opens. The rock walls are dark pearl-hued granite, dotted with pines wherever clefts or ledges exist capable of supporting them; even El Capitan carries its pine-tree half way up its smooth precipice. Frequently the walls are sheer; they look so everywhere. The valley's altitude is 4,000 feet. The walls rise from 2,000 to 6,000 feet higher; the average is a little more than 3,000 feet above the valley floor; Sentinel Dome and Mount Watkins somewhat exceed 4,000 feet; Half Dome nearly attains 5,000 feet; Cloud's Rest soars nearly 6,000 feet. Two large trench-like canyons enter the valley at its head, one on either side of Half Dome. Tenaya Canyon enters from the east in line with the valley, looking as if it were the Valley's upper reach. Merced Canyon enters from the south after curving around the east and south sides of Half Dome. Both are extremely deep. Half Dome's 5,000 feet form one side of each canyon; Mount Watkin's 4,300 feet form the north side of Tenaya Canyon, Glacier Point's 3,200 feet the west side of Merced Canyon. Both canyons are superbly wooded at their outlets, and lead rapidly up to timber-line. Both carry important trails from the Valley floor to the greater park above the rim.