Tendai Buddhism presents itself as a comprehensive Mahāyāna vision in which the Lotus Sūtra stands at the center. The Lotus Sūtra is upheld as the supreme and “perfect” teaching, expressing the One Vehicle (ekayāna) that unifies all Buddhist paths and serves as the standard by which other doctrines are understood. From this perspective, all beings are seen as possessing universal Buddha-nature, and the possibility of Buddhahood in this very body and lifetime (sokushin jōbutsu) is affirmed. The emphasis on universal Buddhahood and the completeness of the Lotus Sūtra gives Tendai a strongly inclusive and harmonizing character, seeking to gather diverse teachings into a single, overarching framework.

Doctrinally, Tendai is marked by the teaching of ichinen sanzen, “three thousand realms in a single moment of thought,” which expresses the idea that all possible realms and states of existence are present in each moment of consciousness. This vision supports a non-dual understanding of reality, in which distinctions such as pure and impure or sacred and profane are ultimately transcended. The school thus encourages seeing everyday experience as permeated by the full depth of the Dharma, rather than as something separate from enlightenment. In this way, the ordinary mind and ultimate reality are understood to interpenetrate completely.

In terms of practice, Tendai draws on a structured approach to meditation that integrates calming and insight, often described through four forms of practice: constant sitting, constant walking, a combination of sitting and walking, and neither sitting nor walking. These forms are not merely technical variations but express the conviction that any posture or activity can become a vehicle for realization when grounded in correct view. Alongside these meditative disciplines, Tendai incorporates esoteric practices—such as mantras, mandalas, and mudrās—aimed at rapid enlightenment, reflecting its willingness to embrace diverse methods within a single path.

Taken together, these principles reveal a tradition that seeks to harmonize gradual and sudden approaches, provisional and ultimate teachings, and exoteric and esoteric methods. The Lotus Sūtra’s “perfect teaching,” the affirmation of universal Buddha-nature, the non-dual vision of reality, and the doctrine of ichinen sanzen all converge to portray a path where every moment, every being, and every practice can be understood as participating in the One Vehicle to Buddhahood.