The recorded sayings of early monks and nuns unmistakably show that Nirvana is experienced as a state of ineffable calm, a joyous tranquillity. The Buddha said: There is a sphere which is neither earth, nor water, nor fire, nor air, which is not the sphere of the infinity of space, nor the sphere of the infinity of consciousness, the sphere of nothingness, the sphere of neither perception nor non-perception, which is neither this world nor the other world, neither sun nor moon. I deny that it is coming or going, enduring, death or birth. It is only the end of suffering.' (Udana 8o) It is one of the wonders of Buddhist art that painters and sculptors have succeededin conveying this ineffable state through the image of the Buddha meditating on his deathbed.
Ref: The World of Buddhism, Bechert & Gombrich, Thames & Hudson, 1984, p 23.