Devotees would often ask Sri Ramakrishna questions about the nature of a knower of Brahman. Of course, such questions have always arisen in the minds of the Sadhakas or seekers. Arjuna in the Bhagavad Gita asks Sri Krishna as to how a man of steady wisdom (Sthitaprajna) behaves. While answering the devotees, Sri Ramakrishna would recall an incident which took place at Dakshineshwar.
Once, a mendicant who presented a strange sight with no clothes on, disheveled hair, etc made an appearance at Dakshineshwar. He straightaway went to the place where dogs were eating from the remnants left over on the leaves by those who had already taken their food. He calmly sat amidst them and started eating from the same leaves. He took handfuls of drainage water and drank them to quench his thirst.
Then he entered the temple and started chanting hymns in such a powerful voice that the very walls of the temple started reverberating the sounds. Sri Ramakrishna could immediately recognize him as a Purna Jnani, a person who had attained complete knowledge of Brahman. Before leaving, in answer to Hriday’s question about attaining true knowledge, he said when one feels no difference between the holy water of river Ganges and the dirty water flowing in the drains, then one may be sure that one has attained the true knowledge. At the highest level of knowledge all distinctions between high and low, pure and impure, good and bad, wicked and holy and so on and so forth vanish, because unitary consciousness is all that exists. It is also called by names such as Brahman or Atman.
Thus Sri Ramakrishna would explain that as one progresses in spiritual life, one understands the utter meaninglessness of the distinctions which we create and fuss over in life.