India, Aug. 29 -- "A time to weep, and a time to laugh; a time to mourn, and a time to dance." - Ecclesiastes 3:4

The Bhagavad Gita speaks of sthita-prajña - steadiness of mind amid fear, anger, pleasure and adversity. Ecclesiastes, from another philosophical tradition, reminds us that human life itself moves through changing emotional seasons.

Across cultures and centuries, humans have tried to understand one of the most elusive aspects of existence: what we feel, why we feel it, and whether we can consciously change our emotional state.

Artificial intelligence is now approaching that ancient question from an entirely different direction.

Machines can understand language, recognise objects, generate images and increasingly act a...