Srimad Bhagavatam Canto 06, Chapter 15, Text 16

SB 6.15.16

tasmad yuvam gramya-pasor
 mama mudha-dhiyah prabhu
andhe tamasi magnasya
 jñana-dipa udiryatam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Because you are great personalities, you can give me real knowledge. I am as foolish as a village animal like a pig or dog because I am merged in the darkness of ignorance. Therefore, please ignite the torch of knowledge to save me.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
This is the way to receive knowledge. One must submit oneself at the lotus feet of great personalities who can actually deliver transcendental knowledge. It is therefore said, tasmad gurum prapadyeta jijñasuh sreya uttamam: “One who is inquisitive to understand the highest goal and benefit of life must approach a bona fide spiritual master and surrender unto him.” Only one who is actually eager to receive knowledge to eradicate the darkness of ignorance is eligible to approach a guru, or spiritual master. The guru should not be approached for material benefits. One should not approach a guru just to cure some disease or receive some miraculous benefit. This is not the way to approach the guru. Tad-vijñanartham: one should approach the guru to understand the transcendental science of spiritual life. Unfortunately, in this Age of Kali there are many bogus gurus who display magic to their disciples, and many foolish disciples want to see such magic for material benefits. These disciples are not interested in pursuing spiritual life to save themselves from the darkness of ignorance. It is said:
om ajñana-timirandhasya
caksur unmilitam yena
 tasmai sri-gurave namah
“I was born in the darkest ignorance, and my spiritual master opened my eyes with the torch of knowledge. I offer my respectful obeisances unto him.” This gives the definition of the guru. Everyone is in the darkness of ignorance. Therefore everyone needs to be enlightened with transcendental knowledge. One who enlightens his disciple and saves him from rotting in the darkness of ignorance in this material world is a true guru.
Srimad Bhagavatam Canto 06, Chapter 15, Text 12-15
Srimad Bhagavatam Canto 06, Chapter 15, Text 17