when the darkness is questioned

Before the spark is lit there is no witness to perceive the difference. The person may be conscious, but is not aware of being conscious. It is completely identified with what it thinks and feels and experiences. The darkness that is in it is of its own creation. When the darkness is questioned, it dissolves. The desire to question is planted by the Guru. In other words, the difference between the person and the witness is as between not knowing and knowing oneself.