He must rest or he would drop to the bottom from exhaustion.

He hooked his right arm over the point of a rock, sat upon a favoring projection below, and decided to wait until his strength was fully restored.
He could not resist the temptation to look up and learn how much yet remained to do.
Could he believe his senses?
He was within a dozen feet of the top! He gasped with amazement, grew faint, and then was thrilled with hope.
He even broke into a cheer, for the knowledge was like nectar to the traveller perishing of thirst in the desert--it was life itself.
All pain, all suffering, all fatigue were forgotten in the blissful knowledge.

He bent to his work with redoubled vigor.

If the supports continued, his stupendous task was virtually ended.
And they did continue.

Not once did the eagerly-feeling hands fail to grasp a projection of some form which could be made to serve his purpose.