Nagarjuna's Root Verses on the Middle Way is the most consequential philosophical text Buddhism produced. Its method is entirely negative — take any position about how things exist, whether they arise from themselves, from another, from both, or from neither, and show that each option collapses. He applies it to motion, time, fire, the self, karma, the Buddha, and nirvana without exception. The point is not scepticism but the middle between existence and non-existence, and the final safeguard is the most important move in the book: emptiness is not a thing that things possess, and anyone who takes emptiness as a view has, in his phrase, been ruined by it.