The word anatha in Sanskrit means one without a master. An acharya (teacher) gives shiksha, which means knowledge; a guru gives deeksha which means heightened awareness. The Guru makes the abstract more real and what you think to be solid appears to be more unreal. Sensitivity and subtlety dawn. Perception of love, not as an emotion, but as the substratum of existence becomes evident. The formless spirit shines through every form in creation and the mystery of life deepens. Then the real journey of life with the guru begins. This journey has four stages.
The first stage is swarupya - to see the formless in the form - that is seeing God in all the forms. Often, one feels more comfortable seeing God as formless rather than with a form, because with a form, one feels a distance, a duality, a fear of rejection and other limitations. In life, all our interactions are with the form, other than in deep sleep and in samadhi. And, if we do not see God in the form, then the waking part of life remains devoid of the Divine.
The second stage is samipya - closeness - that is feeling absolutely close to the form one has chosen and reaching out to the formless. This leads to a sense of intimacy with the whole of creation. In this stage, one overcomes the fear of rejection and other fears. But this is time and space bound.
The third stage is sanidhya, that is feeling the presence of the Divine by which you transcend the limitations of time and space.
The final stage is sayujya, where one is firmly entrenched with the Divine. It is then that one realises that we are one with the Divine. There is a total merging with the beloved and all duality disappears.
In the Upanishads five signs of a satguru are mentioned. In the presence of a satguru, knowledge flourishes, sorrow diminishes, joy wells up without any reason, abundance dawns and all talents manifest.
A guru does not simply stuff the disciple with knowledge; he kindles the life force in the person. In the presence of the guru, one becomes more alive. The pinnacle of intellect is awakened intelligence. The guru invokes not only intelligence but also intellect. Knowledge may not invoke intelligence, but in intelligence, knowledge is inherent.
As no sanchita karma is left in an embodied guru, the self shines through. But all the qualities that we appreciate in a guru are also in our very nature. Respecting the guru simply means honouring our innermost nature.