It is said that once a woman who wished to take a dip in a sacred river left her infant to the care of an ascetic on the bank. Unfortunately, while the saintly man was deep in meditation the child crawled into the waters and drowned. When the mother returned and discovered the tragedy she began to wail. The spiritual man, realizing what had happened, took the body of the dead child from the river, and let his own soul seep into it. The child was revived, but it did not speak. The yogi in the boy's body saw no need to talk. Some years later, the great Shankaracharya happened to run into the seven-year mute child. The philosopher-saint asked the boy who he was, and who his parents were. Now the lad suddenly spoke, and uttered the above words of wisdom.
The life principle manifests itself in a variety of ways. In the traditional worldview they may even be as unearthly beings. Here on earth they could be humans or animals. We as human beings refer to ourselves as of this race or nation, of that creed or caste. Then again we recognize ourselves as being in different stages in life: as child or adult, as spouse or parent or grandparent.
In the midst of all these apparent differences and transformations we often forget that at the core we are all but bits of the same cosmic self.