Śrīmad-Bhāgavatam 3.26.36
SB 3.26.36
Open the full passageSanskrit
mṛdutvaṁ kaṭhinatvaṁ ca śaityam uṣṇatvam eva ca etat sparśasya sparśatvaṁ tan-mātratvaṁ nabhasvataḥ
Translation
Softness and hardness and cold and heat are the distinguishing attributes of touch, which is characterized as the subtle form of air.