The True Meaning of the Guru is hard to reach even through meditation, as has been stated in the scriptures of Ancient India. The Guru then is often misunderstood especially among westerners but also in India where "Gurus" are a common phenomena. This article should help reveal the True Meaning of the Guru...
The Guru you see is a mirror, ideally a perfectly clear mirror. It says in various scriptures that it is impossible to attain Perfection of Enlightenment in Self/God-Realization without the principle of the Guru. This is understood as True if you understand the Guru Principle The Guru is the Light of Awareness which removes the Darkness of Ignorance as is the meaning of the syllables.
In this way it certainly would not be possible for illumination to occur without the Presence of the very Light of That Illumination. That is what the Guru is really the very Light of Enlightenment which Reveals the Ultimate Truth of the Supreme Self. The Guru then is not necessarily a person at all and so Mastery or Perfection of Self/God Realization can occur without the presence of a "Guru" as a Person but not without the Very Light of Consciousness which is the Supreme Self and the Medium of all the Infinite Possibilities of witnessed phenomena.
The Guru as a person is nobody at all as they have surrendered completely to the that Light of the Guru - the Supreme Self, Absolute Reality(Siva). The Guru then manifests through that body or that "person" on a consistent basis as their entire identity has been surrendered to and thus identified in that Reality.
The Guru is the Self-Realized, the Guru then is a Mirror - who can reflect back to "you" everything which appears to stand between "you" and the Enlightenment of Realizing the Supreme Self. Surrendering to the Guru is surrendering to Self-Realization, as the Guru embodies or Represents the All Pervasive Omnipotent ONE Supreme Self - the Light of Awareness which is the Life of All. The ego is that which appears to divide or separate itself from the All Pervasive Omnipotent Indivisible Reality of the ONE.
This is the simplicity of Surrendering that ego to the Ever Illumined Reality of the Self - Pure Primordial Consciousness the source of all Phenomena of Consciousness. That is why the principle of the Guru is cleverly misunderstood by the shape-shifting nature of the ahamkara - ego.
"Your" consciousness is not a separate phenomena of Consciousness from the All-pervasive original Omnipotent Consciousness. Actually there is not "your" mind and "my" mind, there is only Mind an all pervasive Field of Consciousness with unlimited possibilities of experience including "yours" and "mine". Even Science proves this if you have the Light of Awareness on to see the obvious in the Data. Without that Light it is not really clear to see what is there.
The Guru is the Light of Consciousness itself, which allows objects and experiences of cognition to arise. The Guru is Everywhere that Consciousnesses is then, which is all of space and Time, and fully capable of serving Each one in Self-Realization beyond a doubt.
Does this article help you to understand the Principle of the Guru, both in and Beyond a body?