Sankaracarya's Vivekachudamani 414

सर्वोपाधिविनिर्मुक्तं सच्चिदानन्दमद्वयम् ।

भावयात्मानमात्मस्थं न भूयः कल्पसेऽध्वने ॥

sarvopādhivinirmuktaṃ saccidānandamadvayam |

bhāvayātmānamātmasthaṃ na bhūyaḥ kalpase'dhvane ||

(Sankaracarya's Vivekachudamani 414)

Meditate upon that Paramatma which is your Self, which is beyond all limitations, which is Existence-Knowledge-Bliss-Absolute and Non-dual. Never again will you come under the sway of births and deaths.

As confirmed in the Gītā, the fragmental portions of the Supreme exist eternally (sanātana) and are called kṣara; that is, they have a tendency to fall down into material nature. These fragmental portions are eternally so, and even after liberation, the individual soul remains the same—fragmental. But once liberated, he lives an eternal life in bliss and knowledge with the Personality of Godhead. The theory of reflection can be applied to the Supersoul, who is present in each and every individual body and is known as the Paramātmā. He is different from the individual living entity. When the sky is reflected in water, the reflections represent both the sun and the moon and the stars also. The stars can be compared to the living entities and the sun or the moon to the Supreme Lord. The Supreme Lord is superior in position to the living entity, we are forgetful soul deluded by māyā.

We should constantly meditate upon the Paramatma who created us. We are a tiny spark from the bigger light. Because we are in māyā or illusion, we are forgetting our real position. When we become a pure devotee, we will be together with the Supreme Lord which has no limitation, Absolute truth and He is only one God. Only by surrendering to him and going back to him our repetitive birth and death can be stopped. Otherwise we have to take birth again and again.