Siddhartha realized that searching for the Truth not only required determination, but also physical strength. One morning a villiage girl named Sujata cooked a pot of rice porridge and brought it as an offering to Siddhartha. After eating it, Siddhartha felt it was beneficial in improving both his physical and mental strength.

Siddhartha found a bodhi tree on the outskirts of the city of Gaya in eastern India. He sat down facing east, arranged his limbs in meditation posture, and began to meditate under the tree. He vowed not to get up until he reached enlightenment. In the tranquility of deep meditation, he mentally searched and observed, trying to find the source of his own life. Thus he acquired the power of being aware of all his previous lives. Through further insight, he also acquired the power to see all things and to know the future reincarnations of all beings. He came to realize that the unceasing cycle of death and rebirth of all beings is solely a manifestation of one's karma, i.e. the result of one's thoughts and deeds. Finally he observed that the ultimate cause of the cycle of birth and death in the vast sea of worldly suffering, in which mankind and all other beings are immersed, is ignorance and the attachment to transient and illusory pleasure. For those who are unwilling to remain in the cycle of death and rebirth, there is only one way to escape: by the complete destruction or elimination of all lustful desires. Siddhartha  realized that he had delivered himself from all passions and delusions, that he had discovered the cause of all suffering and the way to eliminate it, and that he ha attained enlightenment. He uttered a sigh and then said, "Everyone on earth has the wisdom and virtue of a buddha. It is because of their delusions and attachments that they cannot reveal them or attain enlightenment. If people can get rid of their delusions, their wisdom will naturally appear."

During these days, Mara, the demon king, and his evil army attempted to disrupt Siddhartha's meditation in every way they could. They knew that once Siddhartha attained enlightenment, he would relieve countless people from Mara's control and temptations. The demons transformed themselves into beautiful naked women, tempting Siddhartha with their bodies and hoping to entice him to linger on the pleasures of the past, or even to arouse his desire to return to the palace and enjoy a sensual life. Sidhartha resisted all these temptations with strong willpower. Mara and his cohorts failed to disturb him and they finally fled. When Siddhartha became the Buddha under the bodhi tree by the bank of the Nairanjana River at the crack of dawn, he was thirty-five years old.