Śrīmad-Bhāgavatam · Text 3.26.36
Who is speaking and story frame
मृदुत्वं कठिनत्वं च शैत्यमुष्णत्वमेव च ।
एतत्स्पर्शस्य स्पर्शत्वं तन्मात्रत्वं नभस्वत: ॥ ३६ ॥
mṛdutvaṁ kaṭhinatvaṁ ca
śaityam uṣṇatvam eva ca
etat sparśasya sparśatvaṁ
tan-mātratvaṁ nabhasvataḥ
Softness and hardness and cold and heat are the distinguishing attributes of touch, which is characterized as the subtle form of air.
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