Yāska's Nirukta 14.3

14.3

``apaśyam gopām anipadyamānam ā ca parā ca pathibhiś carantam/
sa sadhrīcīḥ sa visūcīr vasāna ā varīvarti bhuvaneṣv antah/''.
ā varīvarti bhuvaneṣv antari iti/
atha eṣa mahān ātmā sattva lakṣaṇas tat param tad brahma tat satyam tat salilam tad avyaktam tad asparśam tad arūpam tad arasam tad agandham tad amṛtam tat śukram tat nistho bhūta ātmā/
sā eṣā bhūta prakṛtir ity eke/
tat kṣetram tat jñānāt kṣetrajñam anuprāpya nirātmakam/
atha eṣa mahān ātmā trividho bhavati/
sattvam rajas tamas iti/
sattvam tu madhye viśuddham tiṣṭhaty abhitas rajas tamasī/
rajas iti kāma dvesas tamas ity avijñātasya viśuddhyato vibhūtim kurvataḥ kṣetrajña pṛthaktvāya kalpate/
paribhāti liṅgo mahān ātmā tamas liṅgah/
vidyā prakāśa liṅgas tamas1/
ai niścaya liṅga ākāśah/