Buddhist Metaphysics

The Buddha’s statements about Nirvana (the state of unwavering pure Selfhood beyond the illusory world of Samsara) are usually described as ‘metaphysical’ because they seem to be describing something that transcends the physical world. The word 'Metaphysics' means literally “after” (not "beyond" or “above”) “physics", and refers to the arrangement of Aristotle's writings, in which his books on “first philosophy” were placed after the books on “physics”. This is quite distinct to the popular definition of 'beyond or above the physical reality'. The term should be defined thus: ‘pertaining to questions that cannot be answered by any empirical evidence or criteria’.
As Walter Stace observes:
"On this basis most modern thinkers would doubtless class the Buddha’s Nirvana as metaphysical. But it would not be so to Buddha, because he would not, like most modern empiricists, identify experience with sense-experience. The Buddhist adept claims to have direct experience of Nirvana in this life and without waiting for another life. Therefore for Buddha the conception of Nirvana is not metaphysical but empirical"