In the act of hearing, three causes must exist simultaneously, viz., the two ears, sound, and the mind. The same is the case with the perception of touch; the same with that of form; the same with that of taste and smell.
कर्णी शब्दश चित्तं च त्रयः श्रवणसंग्रहे। तथा स्पर्श तथा रूपे तथैव रसगन्धयोः॥