Everyone knows that the security of a building depends greatly upon the kind of foundation it rests upon. No matter how well built it is, no matter how showy the walls may be, if the foundation is not firm and solid, sooner or later it must fall to pieces, unless something is done to repair it. Christopher Wren knew of this danger, and the first thing that he set his workmen to do was to dig down forty feet into the earth to find out if the ground on which he intended to build was quite solid and secure. Doubtless many people laughed at him, and said that he was too particular, but he did not care, and they stopped laughing when it was discovered that right down at the north-east corner there was a pit, and if the new Cathedral had been built over this, sooner or later the ground would have sunk, and the wall of the building have cracked, and in all probability fallen to pieces. However, Dr. Wren made his workmen dig deeper, till they got to the bottom of this pit; then he filled it up with a pier of solid stone. It took him a whole year to do this, but at the end of that time he was ready to begin the church, knowing that underneath it was a foundation that was absolutely secure. Then arose the great Cathedral that we see to-day. It took some thirty years to build, and when it was finished, the highest stone in the lantern that rests on the dome was laid in its place by Sir Christopher Wren’s son. But now we learn something about Sir Christopher that shows that he was a good as well as a clever man. Do you remember what is said in the Bible about people who can rule their own spirits, and are slow to be angry? That they are really greater than the men who conquer cities, and whom the world admires. Tried by this standard, Sir Christopher was a really great man. For he was not only clever enough to build St. Paul’s Cathedral, but he could rule his own spirit, and not vex himself over the way in which his enemies treated him. The story of Sir Christopher Wren’s life--for he was knighted as a reward for his work--is as interesting as any of the stories connected with St. Paul’s Cathedral. He was the son of a Wiltshire clergyman, and his love of architecture dated from a time when the roof of his father’s church had grown so old that it threatened to fall down. And, as often happens in a country parish, there were not very many rich men living there who could give money to pay for the building of a new one. So the Vicar determined that, instead of paying for an architect, he would draw the plans, and superintend the building of the roof himself.