A true spiritual teacher is likened to God and is revered by his loyal students. The word guru means remover of the darkness of ignorance (gu – darkness, ignorance, fear etc ru – remover, dissolver). In these verses, homage is offered to the true teacher who, like God, dissolves the ignorance from within us and fills us with the illumination of wisdom. Homage is also paid to God, the Guru of all Gurus.
Guru mantras are said to originate from various sources: 1) The Guru Stotram from the Vishwamsara Tantram (of which only portions survive today) 2) the Guru Gita that is part of the Skanda Purana. 3) The Guru Stotram is also ascribed to Adi Shankaracharya, however, Adi Shankaracharya composed the Guru Ashtakam.
गुरुर्ब्रह्मा गुरुर्विष्णु र्गुरुर्देवो महेश्वरः।
गुरु साक्षात परब्रह्मा तस्मै श्रीगुरवे नमः॥
Guru saakshaat para-brahmaa
tasmai shree-gurave namaha
Guru is the Creator (Brahma), Guru is the Preserver (Vishnu), Gurudeva is Destroyer(Maheshwara). Guru is the absolute (singular) Lord himself, Salutations to that Sri Guru
अखण्डमण्डलाकारं व्याप्तं येन चराचरम्।
तत्पदं दर्शितं येन तस्मै श्रीगुरवे नमः॥
Vyaaptam yena charaa-charam
Tatpadam darshitam yena
Tasmai shree-gurave namaha
(Which) pervades the entire unbroken form of the circle (of creation), moving and unmoving. To that beautiful and benevolent Guru through whom that state was revealed (to me), salutations.
(translation by Swami Veda Bharati)