By Radhikakrpa dd
A famous Sanskrit shloka reads
Gurur Brahma Gurur Vishnu
Gurur Devo Maheshwara
Guru Sakshat Parabrahma
Tasmai Shri Guruve Namah
Meaning
Guru Brahma – Guru is Brahma also called as Generator, Guru Vishnu means Guru is Vishnu (Vishnu is the Lord who is called organizer), Guru Devo Maheshwara means Guru is the Maheshwara (Shiva or the destroyer), Guru Sakshat Parabrahma means Parbrahma the Supreme Personality of Godhead.
Since Guru leads to a path of light, Guru is Parabrhma.
