The blocks would be heaved out of the barges by dozens of men. Great wooden levers would be inserted under the stones to prise them up to allow the rollers to be slipped under; then hundreds of men would take hold of the long ropes, harnessing themselves like beasts of burden, and drag the stones along. Men with levers would help by thrusting behind; others would walk at the sides to attend to the rollers, and run to the front with new ones directly the last had passed underneath the stone at the back. We can imagine ropes breaking, and mighty stones plunging down the causeway, sweeping scores of poor victims to destruction. Blood and tears as well as labour went to the building of the Pyramids. From first to last, so far as we are able to gather, about 100,000 men slaved for thirty years to build the tomb of Khufu. The site chosen was not exactly level. A little hillock of rock rose on one part of it, and this was cleverly squared off and incorporated into the Pyramid, saving the transport of so many hundreds of tons of rock. The great aim of Khufu, or Cheops, as that of all the other Pharaohs, was to protect his mummy, and prevent thieves getting into his burial chamber. To this end were devised numerous secret passages, all of which show an extraordinary ingenuity in planning, and great engineering skill in execution. The entrance to the Great Pyramid is about 45 feet up on the north face. One of the blocks of stone was made to swing inward on a pivot, and when closed it was quite impossible to locate the entrance. The Pyramid looked quite solid, without a single breach in any one of its sides. So cleverly was the entrance contrived that it baffled men for thousands of years, although countless thieves went over the Pyramid seeking eagerly for a way in. Only a lucky accident could have led the discoverer to touch that particular stone in the right way to make it swing back and disclose the opening.