In order to hasten the assimilation of knowledge and enlightenment, the scriptures strongly suggest that you must seek a guru. A guru must be a realised soul himself, for if an ignorant man starts teaching others, it will be like the blind leading the blind. Instead of doing any good, such teaching only does harm. Only after the realisation of Bhagwan does one attain inner vision. Only then can one diagnose another person’s spiritual malady and give instructions. Thus a teacher is not only aware of universal consciousness, but is also established in it. The guru instructs the disciple to perform certain works and to refrain from others. Again, he advises the pupil to perform action, without desiring the result. It is like getting rid of a disease by means of medicine, under the instructions of a competent physician, Shankaracharya says that the teacher is one who is endowed with the power of furnishing arguments, pros and cons, of understanding questions and answering them. A guru possesses tranquility, self control, compassion and an innate desire to help others. He is well versed with the scriptures, is not attached to worldly and other enjoyments and has renounced attachment to all kinds of actions. He is thus of impeccable conduct, never transgresses rules and is devoid of short comings in the form of jealousy, pride, deceit, anger, ego etc. The sole aim of the guru is to help others and a desire to impart knowledge of the Brahman (ie. Bhagwan/universal consciousness).
Ramkrishna Paramhansa describes the classes of a guru, with a lucid and interesting example.
“There are three classes of physician, superiors, mediocre and inferior. The physician; who just feels the patient’s pulse and just says to him, take the medicine regularly, belongs to the inferior class. He doesn’t care to enquire whether or not the patient has actually taken the medicine. The medicocre physician is he who persuades the patient in various ways to take the medicine and says to him sweetly. ‘My good man, how will you be cured unless you use the medicine? Take this medicine, I have made it myself for you.’ But he who finds the patient, stubbornly refusing to take the medicine, forcing it down his throat, going so far as to put his knee on the patient’s chest, is the best physician. It does not injure the patient, on the contrary it does him good. Like the physician, there are three types of religious teachers. The inferior teacher only gives instructions to the disciple, but makes no enquiry about the progress. The mediocre teacher, for the good of the student makes repeated efforts to bring the instruction home to him, begs him to assimilate it and shows him love in many other ways. But there is a kind of teacher, who goes to the length of using force, when the student is unyielding. I call him the best teacher.”
If a man is initiated by a human guru, he will not achieve anything, if he regards a guru as a mere man. The guru should be regarded as a direct manifestation of the Supreme. Only then can the man have faith in the mantra given by the guru. Once a man has faith, he achieves all. Thus in the ancient times, a student went to live in the ashram of a guru, not just to learn the scriptures, but to also understand how to practise them in his daily life. What differentiates a guru from an arm chair professor (one with bookish knowledge only), is experience. The hallmark of a true guru is experience. Not only does he have knowledge of the Supreme, but he has also experienced Him, which he now teaches his disciple out of concern for his welfare and well being.