According to Ralph Waldo Emerson (1803–1882), there are three great educators of the human mind. They are Nature, Books, and Action. These three influences form the true scholar or “Man Thinking.” These educators help scholars grow in body, mind, and spirit. 

Nature as the First Teacher: Emerson calls Nature the first and most important teacher. He says, Nature is “the opposite of the soul, answering to it part for part.” The scholar learns truth, harmony, and beauty from the natural world. The sky, stars, and seasons teach order and change. Nature makes the scholar calm, wise, and creative. By studying Nature, the scholar knows himself, because both mind and Nature reflect one divine law.

Books as the Second Teacher: Books are the second great influence on the scholar. Emerson says, 

“Books are the best of things, well used; abused, among the worst.” 

Action as the Third Teacher: The third great educator is Action. Emerson believes that ideas must grow from experience. He says, thought and action must go together. By working, struggling, and living among people, the scholar gains truth. Action gives life to learning. Without it, the scholar remains weak and incomplete. Through action, he learns courage, patience, and wisdom.

In short, Emerson shows that Nature, Books, and Action together make a true scholar. Nature teaches truth, Books give knowledge, and Action gives strength. These three build the complete “Man Thinking,” who learns freely and serves mankind wisely.