हसितरुदितादिसंभ्रमभयश्रमव्याधिपीडितार्थेषु । नानाभावोपगतं कार्यमुरो नाट्ययोगेषु ॥ २३१॥
The breast is recognized as Prakampita (shaking) in situations of laughter, weeping, confusion, fear, fatigue, and ailments. It is also associated with various emotional states in dramatic performances.
english translation