SB 11.10.12
acaryo ’ranir adyah syad
ante-vasy uttararanih
tat-sandhanam pravacanam
vidya-sandhih sukhavahah
Translation:
The spiritual master can be compared to the lower kindling stick, the disciple to the upper kindling stick, and the instruction given by the guru to the third stick placed in between. The transcendental knowledge communicated from guru to disciple is compared to the fire arising from the contact of these, which burns the darkness of ignorance to ashes, bringing great happiness both to guru and disciple.
Purport:
When the darkness of ignorance is burned to ashes, the dangerous life of ignorance is also eradicated, and one can work for his true self-interest in full knowledge. In this verse the word adyah means “original,” and it indicates the spiritual master, who is compared to the sacred kindling stick held below. From the spiritual master transcendental knowledge, like fire, is spread to the disciple. Just as friction between two sticks of firewood produces fire, similarly, bona fide contact between the spiritual master, who is the representative of Krsna, and a sincere disciple produces the fire of knowledge. When the disciple takes shelter of the lotus feet of the spiritual master, he automatically acquires perfect knowledge of his original, spiritual form.