In his collection of essays, Zen and the Taming of the Bull, the learned Buddhist teacher Walpola Rahula introduces the well-known series of Zen pictures that illustrate the way to enlightenment. In the version that Rahula discusses, the bull – a metaphor for the unruly mind – is depicted as changing gradually from black to shining white. ‘The underlying idea’, he says, ‘is that the mind, which is naturally pure, is polluted by extraneous impurities and that it could and should be cleansed through discipline and meditation’. The yogi or seeker after truth begins by confronting the wild beast, catches it and then tethers it. He ties it to a tree and trains it to follow after him. In the next picture, the bull lies passively by the river while the yogi plays his flute. Then we find the bull drinking from the water while the yogi sleeps in the background. In the next, bull and seeker stand observing each other. In the penultimate picture, the seeker is alone; the bull has been transcended altogether. The final picture in Rahula’s series is nothing more than a round circle; now both bull and self have been transcended and all traces of ego eradicated.

That is as far as Rahula’s account takes us. His aim is to link the contemporary practice of Zen, where the emphasis is usually on ‘sudden’ enlightenment, with the most ancient traditions, particularly his own Theravada, with its disciplines and meditative practices that build up a mindful attention to the present moment. But in the more familiar Japanese versions, which go back to the fifteenth century, a further stage is indicated: what is often called the ‘return to the marketplace’. Here we find the yogi encountering others and talking with them. One commentary, by the Zen scholar Yanagida Seizan says:

Depicted here is something of the spirit of the Mahayana, with its paradoxical assertion that samsara is nirvana and nirvana samsara. Ultimately, the round of rebirth, life in the world as we experience it, is no different from the truth discovered in that moment of enlightenment. To be enlightened does not entail some escape to a transcendent realm but the attaining of freedom from all forms of attachment – whether from control by the inner passions or, more paradoxically, from the very desire for some ‘spiritual realm’. What Buddhists refer to as upaya, ‘skilful means’, is as much a quality of detachment that values the potential for enlightenment in the world of ordinary everyday experience as it is a practical exercise of compassion that leads and teaches other suffering sentient beings.