There is sorrow in finitude. The Self is beyond time, space and objects. It is infinite and hence of the nature of absolute happiness.
Adi ShankaraThe witness of the three states of consciousness [waking, dream and deep sleep] and of the nature of Existence-Consciousness-Bliss is the Self
Adi ShankaraEach thing tends to move towards its own nature. I always desire happiness which is my true nature. My nature is never a burden to me. Happiness is never a burden to me, whilst sorrow is.
Adi ShankaraBut the jiva [living being] is endowed with ego and his knowledge is limited, whereas Ishwar is without ego and is omniscient.
Adi Shankara