The rishis of old attained the Knowledge of Brahman. One cannot have this so long as there is the slightest trace of worldliness. How hard the rishis laboured ! Early in the morning they would go away from the hermitage, and would spend the whole day in solitude, meditating on Brahman. At night they would return to the hermitage and eat a little fruit or roots. They kept their mind aloof from the objects of sight, hearing, touch, and other things of a worldly nature. Only thus did they realize Brahman as their own inner conciousness.
RamakrishnaThat knowledge which purifies the mind and heart alone is true Knowledge, all else is only a negation of Knowledge.
RamakrishnaImagine a limitless expanse of water: above and below, before and behind, right and left, everywhere there is water. In that water is placed a jar filled with water. There is water inside the jar and water outside, but the jar is still there. The 'I' is the jar.
Ramakrishna