Chapter-18, Verse 69

Ashtavakra Gita Verse 18.69 

महदादि जगद्द्वैतं नाममात्रविजृम्भितम् ।

विहाय शुद्धबोधस्य किं कृत्यमवशिष्यते ॥ ६९ ॥

What remains to be done by one who is Pure Consciousness? He has renounced the pluralistic world, which begins with mahat (total intellect) and is manifested merely by names.

The meaning of this verse is that the one who has Realized the non-dual nature of Reality, which is beyond the names and forms of the phenomenal world, has nothing left to accomplish. He is free from all desires and attachments, and rests in his own True Nature, which is Pure Consciousness. He does not identify with the body, mind, senses, or ego, but sees them as mere appearances in his own Self. He is not affected by the dualities of pleasure and pain, gain and loss, honor and dishonor, etc. He is the Witness of all, but not the doer or the enjoyer. He is content and peaceful in himself, and does not depend on anything external for his happiness.

This verse is similar to some other verses from the Vedic texts, which also express the idea of non-duality and Self-Realization. 

 - Chandogya Upanishad 6.2.1

एकमेवाद्वितीयं ब्रह्म नेह नानास्ति किञ्चन ।

भेदभेदवादिनो वदन्ति ते निर्विकल्पकाः ॥

Brahman is one without a second; there is no diversity here whatsoever. Those who say that there is difference and non-difference are devoid of discrimination.

 - Chandogya Upanishad 3.14.1

सर्वं खल्विदं ब्रह्म ।

All this is Brahman. 

These verses assert that the Ultimate Reality is One, indivisible, and identical with the Self. There is no distinction between the individual and the universal, the subject and the object, the Knower and the Known. All multiplicity and diversity are illusory, and the result of ignorance. The goal of human life is to Realize this Truth, and to overcome the bondage of the ego and the world. This is the essence of the Vedantic philosophy, which is derived from the Upanishads, the concluding part of the Vedas.