SHABD or Word (the Primal Sound Current) is the only Guru for the entire world and Surat (individual consciousness) is the only disciple, as the latter cannot do without the former. In fact, there is the principle of unity, for God is One, though He has manifested Himself variously.
   But as we look the other way and turn to the world abounding in diverse forms, we see a Pole-star shining in its majesty reflecting the Light of Heaven.
   Such a pure soul (Word made flesh or Godman) with authority to give spiritual instructions to the seekers after God, is as much a Guru as the Shabd Itself, for he himself is a living embodiment of Shabd and with Shabd as stock in trade freely distributes It to whomever he likes.
   Kabir speaks of himself:

        I come from the Kingdom of God to administer the Law of God.

Guru Nanak, too, was invested with a similar authority to impart spiritual instructions when he was in deep meditation in Veiny Nadi (the Water of Spirituality within).
   Both of them were Param Sant Satgurus.  Kabir Sahib was born in 1398 A.D. at Lahr Talao near Benaras and passed away in 1518. Guru Nanak was born in 1469 A.D. at Talwandi, and left the physical plane at Kartarpur in 1539. Thus both of them were contemporaries for about forty-nine years, from 1469 to 1518. In the same way Shamas-i-Tabrez and Maulana Rumi were also contemporaries for some time.
   Again, Guru Angad and Dadu Sahib lived together from 1504 to 1552.  So also, Guru Arjan and Dharam. Das from 1561 to 1606.  These instances go to show that there can be more than one Guru at the same time, but a person cannot have more than one Guru for spiritual perfection. It does not matter even if a Guru after initiating a person passes away.
   Once he initiates an individual, the Subtle Form of  the Master gets embedded in the disciple for he becomes from that moment the disciple's ideal and his instructions gradually begin to bear fruit.
   There is no power on earth that can render sterile the seed sown by a Master Soul. Master never dies. He may leave the body, as anyone else does, but he is more than a mere body. He is an ideal, a living Sound Current or a Life Principle that gives Life and Light to the entire world.
   After his passing away one may derive benefit from the Satsang conducted by a Gurmukh who is carrying on the duties of Guru, and may consult him in case he has some difficulty. It is, however, of the utmost importance that the Master is not to be changed on any account.
   Loyalty to the Master who has initiated the spirit and to whom the spirit has pledged his troth demands the recognition that the Master is competent to impart further guidance and instructions, even when he is working on the spiritual plane after having left the physical world.