From the darkness of false ego, the first of the five elements, namely the sky, is generated. Its subtle form is the quality of sound, exactly as the seer is in relationship with the seen.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तामसादपि भूतादेर्विकुर्वाणादभून्नभः । तस्य मात्रा गुणः शब्दो लिङ्गं यद्द्रष्टृदृश्ययोः
tāmasādapi bhūtādervikurvāṇādabhūnnabhaḥ | tasya mātrā guṇaḥ śabdo liṅgaṃ yaddraṣṭṛdṛśyayoḥ
SB 2.5.25