Conversation between Adi Sankaracharya and his student.
Student: Why does the soul suffer?
Sankaracharya: Because of the body in which the Soul exists.
Student: Why does soul take body?
Sankaracharya: Because of our Karma(Past deeds)
Student: What is this cause for this Karma?
Sankaracharya: Wants,desires and hatred is the cause of Karma.
Student: What is the origin of Wants,desires and hatred?
Sankaracharya: Lack of knowledge
Student: What is the reason for Lack of Knowledge?
Student: Why is one Ignorant?
Sankaracharya: Ignorance has not beginning or end.It is one which cannot be defined and causes the soul to fall in the cycle of Birth and Death.It is waste of time for us to find the cause of ignorance and sorrow.We always should try to get enlightened and put an end to this viscous cycle.