SB 1.5.5

vyāsa uvāca
asty eva me sarvam idaṁ tvayoktaṁ
 tathāpi nātmā parituṣyate me
tan-mūlam avyaktam agādha-bodhaṁ
 pṛcchāmahe tvātma-bhavātma-bhūtam
Synonyms: 
vyāsaḥ — Vyāsa; uvāca — said; asti — there is; eva — certainly; me — mine; sarvam — all; idam — this; tvayā — by you; uktam — uttered; tathāpi — and yet; na — not; ātmā — self; parituṣyate — does pacify; me — unto me; tat — of which; mūlam — root; avyaktam — undetected; agādha-bodham — the man of unlimited knowledge; pṛcchāmahe — do inquire; tvā — unto you; ātma-bhava — self-born; ātma-bhūtam — offspring.
Translation: 
Śrī Vyāsadeva said: All you have said about me is perfectly correct. Despite all this, I am not pacified. I therefore question you about the root cause of my dissatisfaction, for you are a man of unlimited knowledge due to your being the offspring of one [Brahmā] who is self-born [without mundane father and mother].
Purport: 

In the material world everyone is engrossed with the idea of identifying the body or the mind with the self. As such, all knowledge disseminated in the material world is related either with the body or with the mind, and that is the root cause of all despondencies. This is not always detected, even though one may be the greatest erudite scholar in materialistic knowledge. It is good, therefore, to approach a personality like Nārada to solve the root cause of all despondencies. Why Nārada should be approached is explained below.