Two birds perching on the same tree.

The supreme self, Brahman as the indwelling spirit as two birds perching on the same tree the body, the former eats the fruits of the tree results of karma some sweet and some bitter and experiences joy and sorrow. the Later is sitting majestically, even calm and collected, never touching those fruits. when the jeevatma realises the greatness of the Paramatma, he becomes free from all sorrow and suffering.
Several modes of upasana or sadhana are prescribed for the jiva to recover its original state though it is never mentioned how the ever free atman became the Jiva. Any way since we find ourselves here we have to reach the other shore and this the experienced and mighty who have made upteen number of attempts have laid down the procedure so to say.
The disciple should practice reflection and meditation on the atman which will result in realisation. He then sees all beings inhimself and himself in all. He neither feels special attraction nor repulsion for others. he is able to feel the power of the atman behind every thought and act of his. he clearly perceives that all the attachments bonds of his heart which tie him down in what he thinks reality are broken. he experiences great joy and bliss. thus inside and outside he sees the same thus experiencing incomparable bliss.