This metaphysics is entailed in the Tiantai teaching of the "three truths", which is an extension of the Mādhyamaka two truths doctrine. The three truths are: the conventional truth of appearance, the truth of emptiness (shunyata) and the third truth of 'the exclusive Center' (但中 "danzhong") or middle way, which is beyond conventional truth and emptiness. This third truth is the Absolute and expressed by the claim that nothing is "Neither-Same-Nor-Different" than anything else, but rather each 'thing' is the absolute totality of all things manifesting as a particular, everything is mutually contained within each thing. Everything is a reflection of 'The Ultimate Reality of All Appearances'(諸法實相 zhufashixiang) and each thought "contains three thousand worlds". This perspective allows the Tiantai school to state such seemingly paradoxical things as "evil is ineradicable from the highest good, Buddhahood." Moreover, in Tiantai, nirvana and samsara are ultimately the same; as Zhiyi writes, "A single, unalloyed reality is all there is – no entities whatever exist outside of it."