Buddha's Enlightenment

With the ability to see through past, present and future, Gautama then penetrated the secrets of the origin of the universe, the birth and history of the planet Earth, the rise and fall of civilizations, his own past incarnations and the future history of humanity. When his mind became still and free from attachment, he experienced his spiritual body expanding to become as big as the whole universe, leaving his physical body behind beneath the pipal tree. This experience distinguishes one who has unlocked the door to the kingdom of mind, and it is proof of one who has fully grasped the feeling of the perfect freedom of the soul through the spiritual senses. Gautama's realization that the soul and the physical body are different marked the very first step for his great enlightenment.

Having attained enlightenment and become what we now know as the Buddha, Gautama thought he could not wait to convey what he had understood to as many people as he could, as quickly as possible. He felt that if he kept the experience to himself, his life would have been meaningless, so when he went begging, he did not simply receive alms but tried to take every opportunity to tell to people he met that he had become enlightened, and to share his experiences with them. But nobody would listen. People said that he must have gone crazy, and that he was conceited, because they thought that enlightenment could not be attained unless one studied under teacher.

His desire to convey that exhilarating experience of enlightenment to others was so intense that he set out to look for the five astetics he knew from before and talk to them. They witnessed that Gautama had reached the same level of enlightenment as they teacher in such a short time, they decided to leave their teacher and go through ascetic training with Gautama. That is how his teaching of the Law started.

From the book: The essence of Buddha The path to Enlightenment by Ryuho Okawa