What is thought? It is not Matter, nor Spirit. It is not a Thing; but a Power and Force. I make upon a paper certain conventional marks, that represent that Thought. There is no Power or Virtue in the marks I write, but only in the Thought which they tell to others. I die, but the Thought still lives. It is a Power. The fact that Thought continues to exist an instant, after it makes its appearance in the soul, proves it immortal: for there is nothing conceivable that can destroy it. The spoken words, being mere sounds, may vanish into thin air, and the written ones, mere marks, be burned, erased, destroyed: but the thought itself lives still, and must live on forever.