In Chih-i’s view there can be no doubt that the ultimate truth revealed in the Lotus Sutra is the inherent Buddha-nature. Chih-i felt that the Lotus Sutra surpasses all others in its articulation, demonstration, and explanation of the promise that all sentient beings can become Buddhas. The doctrine of universal Buddhahood is proclaimed in the second chapter, where Śākyamuni explains that instead of three “vehicles,” or ultimate goals for three different kinds of beings, the śrāvakas, pratyekabuddhas, and bodhisattvas, there is only one goal, Buddhahood, for all. The sutra also demonstrates the universality of Buddhahood by depicting the dragon king’s daughter (possessing the disadvantages of being both female and a reptile) instantaneously attaining enlightenment, and by predicting the future enlightenment of the Buddha’s cousin, Devadatta, who had committed the most heinous evils — attempting to kill the Buddha and to disrupt the Buddhist Saṃgha. Chih-i believed that only a doctrine of universal Buddha-nature could justify the sutra’s unqualified promise that all sentient beings can become Buddhas. The sutra’s visionary representation of the identity of the Buddha Śākyamuni with all reality may therefore be taken as a revelation of the Buddha-nature inherent in all things.
A Buddhist Kaleidoscope; Susan Mattis, Chih-i and the Subtle Dharma of the Lotus Sutra: Emptiness or Buddha-nature?, Page 246-247