Bhashya
नन्वात्मनि ज्ञाते सर्वमन्यज्ज्ञायत इति ज्ञाने प्रकृते, कथं लाभोऽप्रकृत उच्यत इति ; न, ज्ञानलाभयोरेकार्थत्वस्य विवक्षितत्वात् ।आत्मनो ह्यलाभोऽज्ञानमेव ; तस्माज्ज्ञान-मेवात्मनो लाभः ; न अनात्मलाभवत् अप्राप्तप्राप्तिलक्षणआत्मलाभः, लब्धृलब्धव्ययोर्भेदाभावात् ।यत्र ह्यात्मनो-ऽनात्मा लब्धव्यो भवति, तत्रात्मा लब्धा, लब्धव्यो-ऽनात्मा ।स चाप्राप्तः उत्पाद्यादिक्रियाव्यवहितः, कारकवि-शेषोपादानेन क्रियाविशेषमुत्पाद्य लब्धव्यः ।स त्वप्राप्तप्रा-प्तिलक्षणोऽनित्यः, मिथ्याज्ञानजनितकामक्रियाप्रभवत्वात्--स्वप्ने पुत्रादिलाभवत् ।अयं तु तद्विपरीत आत्मा ।आत्म-त्वादेव नोत्पाद्यादिक्रियाव्यवहितः ।नित्यलब्धस्वरूपत्वेऽपिअविद्यामात्रं व्यवधानम् ।यथा गृह्यमाणाया अपि शुक्ति-काया विपर्ययेण रजताभासाया अग्रहणं विपरीतज्ञानव्यव-धानमात्रम् , तथा ग्रहणं ज्ञानमात्रमेव, विपरीतज्ञानव्यवधा-नापोहार्थत्वाज्ज्ञानस्य ; एवमिहाप्यात्मनोऽलाभः अविद्यामा-त्रव्यवधानम् ; तस्माद्विद्यया तदपोहनमात्रमेव लाभः, नान्यःकदाचिदप्युपपद्यते ।तस्मादात्मलाभे ज्ञानादर्थान्तरसाधनस्यआनर्थक्यं वक्ष्यामः ।तस्मान्निराशङ्कमेव ज्ञानलाभयोरेका-र्थत्वं विवक्षन्नाह- ज्ञानं प्रकृत्य-- 'अनुविन्देत' इति ;
In plain words
You might ask: since we are discussing the knowledge by which everything is known, why does the text suddenly speak of 'attaining' the Self as if it were a different topic? The answer is that knowing the Self and attaining the Self mean the exact same thing. Not possessing the Self is nothing but ignorance of it; therefore, realizing it is itself its attainment. This is not like acquiring an external object that you do not already have. Here, there is no difference between the one who attains and the thing attained. When you seek an external object, you are separate from it, and you must act to get it. But the Self is your very nature; it is already eternally attained, and only a thin veil of ignorance makes it seem lost—just as a shell is mistaken for silver until you look closely.
Close to the Sanskrit
If it is objected: 'When the Self is known, everything else is known' being the topic of knowledge under discussion, how is 'attainment' spoken of as if it were not under discussion? We reply: No, because the identity of meaning of knowledge and attainment is intended. For the non-attainment of the Self is indeed mere ignorance; therefore, knowledge itself is the attainment of the Self. It is not an attainment of the Self characterized by the acquisition of the unobtained, like the attainment of the non-self, because of the absence of difference between the attainer and the to-be-attained...