What is the meaning of internal light?

If each man followed the internal light that is implanted in him at his birth, and which it is the duty of his parents and teachers to develop to its most beautiful proportions, he would want no clergyman to teach him how to act—no creeds to guide him—no ceremonials to bind him.

He would have within him the true Spirit of God to enlighten and direct him. 

It would be a lamp unto his feet and a light unto his path, and justice, love and wisdom would mark his progress onward. This, my friends, is what God in his wisdom has always designed for man. 

This is what He intends him to arrive at, and He is gradually bringing the result about.

—Joshua, son of Nun in Spirit