The sky is a product of sound, and sound is the transformation of egoistic ignorance. In other words, the sky is the symbolic representation of the Supreme Soul.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
कालमायांशयोगेन भगवद्वीक्षितं नभः । नभसोऽनुसृतं स्पर्शं विकुर्वन्निर्ममेऽनिलम्
kālamāyāṃśayogena bhagavadvīkṣitaṃ nabhaḥ | nabhaso'nusṛtaṃ sparśaṃ vikurvannirmame'nilam
SB 3.5.32