In Sikhism the word 'Guru' is, thus, defined as the Light that dispels all darkness, and that is called JOT (Divine Light). Guru Nanak was, therefore, the EMBODIMENT of Divine Light:

'Guru Nanak is embodiment of the Light of God.' (1192, Guru Granth Sahib)

The Guru in Sikhism is a perfect Prophet or Messenger of God in whom the Light of God shines fully, visibly and completely. Guru is in union with Divine. Thus he ushers the devotees, the seekers of Truth into a spiritual birth. Through him the Glory of the Lord is transmitted to humanity. On account of his Divine prerogatives, the Guru, though human in form, is Divine in Spirit.

Literally Guru Nanak's body was a platform from which God Himself spoke and delivered His message Gurbani (Divine Word). God manifested Himself through Guru Nanak:

'In the true Guru (Nanak) He installed His Own Spirit Through him, God speaketh Himself.' (1279)

God is in the Guru and Guru is in God. Though God is everywhere and in everybody but His traits are illuminated through the Guru. The Jot (Divine Light) that enshrined Guru Nanak's body and the Primal Jot of God are, therefore, one and the same:

'O Nanak, Jot of Nanak and God are one.' (865)