Sri Ramakrishna : Self Knowledge is discussed in Ashtavakra Samhita

Sri Ramakrishna (to M.) : "Self-Knowledge is discussed in the Ashtavakra Samhita. The non-dualists say, 'Soham', that is, 'I am the Supreme Self.' This is the view of the sannyasis of the Vedantic school. But this is not the right attitude for householders, who are conscious of doing everything themselves. That being so, how can they declare, 'I am That, the actionless Supreme Self?

According to the non-dualists the Self is unattached. Good and bad, virtue and vice, and the other pairs of opposites, cannot in any way injure the Self, though they undoubtedly afflict those who have identified themselves with their bodies. Smoke soils the wall, certainly, but it cannot in any way affect akasa, space. Following the Vedantists of this class, Krishnakishore used to say, 'I am Kha', meaning akasa. Being a great devotee, he could say that with some justification; but it is not becoming for others to do so.

"But to feel that one is a free soul is very good. By constantly repeating, 'I am free, I am free', a man verily becomes free. On the other hand, by constantly repeating, 'I am bound, I am bound', he certainly becomes bound to worldliness. The fool who says only, 'I am a sinner, I am a sinner', verily drowns himself in worldliness. One should rather say: 'I have chanted the name of God. How can I be a sinner? How can I be bound?'