In plain words
Then He said, ‘The light is in Me.’ He imagined that He was living in the light. The light is not outside; that is, it is in Me. He thought, ‘The light is in Me.’ That is the reflection of the inner being. The person within is seen outside. As He went on developing it in this way, at last He said, ‘I myself am the light: I am the light.’ I am in the light, the light is in me, I am the light. All these belong with Dvaita, Viśiṣṭādvaita and Advaita. With the aim of proclaiming Advaita to the world, Śaṅkara at first went on regarding himself as a servant. But unhappily, before Śaṅkara's third year was out, his father Śivaguru died; some ten days before, a light appeared to Śivaguru. ‘Perform the upanayana saṃskāra for your son,’ he said. The light itself spoke. That is: the light is in me. Soon, within the third year, Śivaguru performed the upanayana saṃskāra for his son. This little boy began the Gāyatrī mantra. The father died in that very third year. The mother bore her grief and went on bringing up this boy. First she placed him with a guru. That guru went on teaching him many branches of learning. The four Vedas and the six Śāstras he learnt before his sixteenth year was out. Even 50 years would not be enough to study the four Vedas and the six Śāstras. This child was very special. One look was enough. Even the guru was greatly amazed. The mother could not bear her sorrow. One day she went to the guru and asked, ‘We must get our boy married.’ The boy said: ‘I do not want marriage. I long to take sannyāsa. I have resolved to offer my body, my mind, my all to God alone. This is not my power, not my property, not my wealth. This is power God has given. I am one offered up to God.’ ‘I do not want marriage,’ he said. He insisted on taking sannyāsa. His mother Āryāmbā wept a great deal. That is only natural in the world! One day the mother was going to the Kāverī for water. He was following right behind her. ‘Mother! Give me leave, give me leave!’ he kept saying.