According to St Basil, the monk's whole life should be a season of prayer, both public prayer and private prayer. That is what the monks of Mount Athos are there to do. That is the basis of their entire way of life. Athos is sometimes called 'the mountain of silence', but as one living Athonite has written, 'here you can hear the hum of unceasing prayer.' The book explores all dimensions of this mystery, beginning with the deceptively simple question 'what is prayer?' Subsequent papers consider various aspects of prayer as practised on Athos both in public and in private: the prayer of the church and the prayer of the cell, prayer when working, prayer when painting icons, the musical tradition of prayer and the poetic tradition, culminating in the Jesus Prayer or prayer of the heart which is the foundation of the current renewal of monasticism on Athos. Most of the papers in this book were delivered at a conference held by the Friends of Mount Athos in Cambridge in March 2019.