Writing in the 1600s, Descartes famously pronounced ‘Cogito ergo sum’, ‘I think therefore I am’, as his first principle. Perception, however, has shifted. Where before the words 'I think...' dominated discourse, now 'I feel...' can be heard in cafes, barbers, coffee shops, schools and stations. ‘Sentio ergo sum’, ‘I feel therefore I am’, takes centre stage.