Suppose I were to go down through this audience and ask you to introduce me to the great inventors who live here in Philadelphia. "The inventors of Philadelphia," you would say "Why we don't have any in Philadelphia. It is too slow to invent anything." But you do have just as great inventors, and they are here in this audience, as ever invented a machine. But the probability is that the greatest inventor to benefit the world with his discovery is some person, perhaps some lady, who thinks she could not invent anything. Did you ever study the history of invention and see how strange it was that the man who made the greatest discovery did it without any previous idea that he was an inventor? Who are the great inventors? They are persons with plain, straightforward common sense, who saw a need in the world and immediately applied themselves to supply that need. If you want to invent anything, don't try to find it in the wheels in your head nor the wheels in your machine, but first find out what the people need, and then apply yourself to that need, and this leads to invention on the part of people you would not dream of before. The great inventors are simply great men; the greater the man the more simple the man; and the more simple a machine, the more valuable it is. Did you ever know a really great man? His ways are so simple, so common, so plain, that you think any one could do what he is doing. So it is with the great men the world over. If you know a really great man, a neighbor of yours, you can go right up to him and say, "How are you, Jim, good morning, Sam." Of course you can, for they are always so simple. When I wrote the life of General Garfield, one of his neighbors took me to his back door, and shouted, "Jim, Jim, Jim!" and very soon "Jim" came to the door and General Garfield let me in--one of the grandest men of our century. The great men of the world are ever so. I was down in Virginia and went up to an educational institution and was directed to a man who was setting out a tree. I approached him and said, "Do you think it would be possible for me to see General Robert B. Lee, the President of the University?" He said, "Sir, I am General Lee." Of course, when you meet such a man, so noble a man as that, you will find him a simple, plain man. Greatness is always just so modest and great inventions are simple.