Mainstream Buddhist doctrine before Zhanran generally reserved the possession of Buddha-nature, the innate capacity for awakening, to sentient beings, those capable of suffering, perceiving and eventually attaining enlightenment. Zhanran argued for a considerably wider claim: that insentient things, grass, trees, tiles and stones among the examples given, also possess Buddha-nature, since in Tiantai's own metaphysics every particular phenomenon already contains the whole of reality within it, so nothing can be excluded without contradicting the school's own core teaching of mutual containment. The position was controversial even within Tiantai circles and was read by rival schools as either a bold consistency or an overreach, but it became one of the most distinctive and often cited features of later Tiantai philosophy, discussed for centuries after Zhanran by commentators working out its implications for practice and cosmology alike. Scholars of Chinese Buddhism read the doctrine as part of Zhanran's broader project of demonstrating that Tiantai's system was more thorough and more consistent than the newer Huayan school then eclipsing it in prestige at the Tang court, turning what could have been read as a narrow technical dispute into a claim about which school had actually reasoned its own first principles through to their end.