King Trần Thái Tông, though holding the throne, practiced diligently and once sought to leave home and ordain at Yên Tử Mountain, until Zen Master Viên Chứng advised him that “practice is not only on the mountain or in the temple,” but right in the palace, “while governing the country, the king can still study the Buddha’s teachings and practice the true Dharma.” He walked steadily in meditation with the mantra “each step touches the earth of reality,” every footstep touching “the ground of truth,” and transmitted this method to future generations. The Pure Land, according to the profound teachings of the Buddha, is not something to wait for after death or in the Western direction, but is “the Pure Land of the mind” present here and now – “the Pure Land in our hands” –, where each breath, each step with mindfulness and concentration brings us back to the present moment and to “the wonders of life” such as the blue sky, white clouds, birds singing, pines whispering, and flowers blooming.

During the period of the Lesser Vehicle after the Buddha’s passing, about twenty schools arose, among which the three main schools were:

1. Theravāda (School of the Elders)
2. Mahāsaṅghika (Great Assembly School)
3. Sarvāstivāda–Vibhajyavāda (School of All Exists–Distinctionists)

Sarvāstivāda and Mahāsaṅghika were pioneers in developing the Avadāna literature (Stories of Deeds) and Jātaka (stories of previous lives) – where the Bodhisattva ideal of the Lesser Vehicle was early revealed. Sarvāstivāda also added “emptiness” to the three Dharma seals (suffering, impermanence, non-self) to form the four Dharma seals, and deeply analyzed the five aggregates, the twelve sense bases, the Four Noble Truths, and the Noble Eightfold Path – heritages that the Mahāyāna later received and developed.