Thought.

Bell, Circular Tetrahedral Kite, 1908

Don't keep forever on the public road,going only where others have gone, and following one after the other like a flock of sheep. Leave the beaten track occasionally and dive into the woods.  Every time you do so you will be certain to find something that you have never seen before. Of course it will be a little thing, but do not ignore it. Follow it up, explore all around it; one discovery will lead to another, and before you know it you will have something worth thinking about to occupy your mind. All really big discoveries are the results of thought.

Alexander Graham Bell