What is complete knowledge?

What is complete knowledge? What does it mean to have complete knowledge?

There is a story in Chandogya Upanishad, a principle text within the Vedas, about a young boy, Shvetaketu, whose father sent him to a teacher to learn about the spiritual life. When he returned home twelve years later, the boy was arrogant; proud of the knowledge he had gained. His father, Uddalaka, noticing this, said: “You seem to be proud of all this learning, but did you ask your teacher for that spiritual wisdom which enables you to hear the unheard, think the unthought and know the unknown?”
Their dialogue continues: “What is that wisdom, Father?” asked the son.