From Ramana Maharshi

http://www.ramana-maharshi.org/books.htm

1. What are the marks of a real teacher (Sadguru)?

Steady abidance in the Self, looking at all with an equal eye, unshakeable courage at all times, in all places and circumstances, etc.

2. What are the marks of an earnest disciple (sadsisya)?

An intense longing for the removal of sorrow and attainment of joy and an intense aversion for all kinds of mundane pleasure.

3. What are the characteristics of instruction (upadesa)?

The word 'upadesa' means : 'near the place or seat' (upa - near, desa - place or seat). The Guru who is the embodiment of that which is indicated by the terms sat, chit, and ananda (existence, consciousness and bliss), prevents the disciple who, on account of his acceptance of the forms of the objects of the senses, has swerved from his true state and is consequently distressed and buffeted by joys and sorrows, from continuing so and establishes him in his own real nature without differentiation.

Upadesa also means showing a distant object quite near. It is brought home to the disciple that the Brahman which he believes to be distant and different from himself is near and not different from himself.

4. If it be true that the Guru is one's own Self (atman), what is the principle underlying the doctrine which says that, however learned a disciple may be or whatever occult powers he may possess, he cannot attain self-realization (atma-siddhi) without the grace of the Guru?

Although in absolute truth the state of the Guru is that of oneself it is very hard for the Self which has become the individual soul (jiva) through ignorance to realize its true state or nature without the grace of the Guru.

All mental concepts are controlled by the mere presence of the real Guru. If he were to say to one who arrogantly claims that he has seen the further shore of the ocean of learning or one who claims arrogantly that he can perform deeds which are well-nigh impossible, "Yes, you learnt all that is to be learnt, but have you learnt (to know) yourself? And you who are capable of performing deeds which are almost impossible, have you seen yourself?", they will bow their heads (in shame) and remain silent. Thus it is evident that only by the grace of the Guru and by no other accomplishment is it possible to know oneself.