Essentials of the One Vehicle Teaching, The ［一乗要決］ ( Ichijō-yōketsu): A treatise written around 1006 by Genshin, a priest of the Japanese Tendai school. Based on the Tendai doctrine, it stresses the one vehicle teaching of the Lotus Sutra and asserts that all people possess the Buddha nature. It attacks the “five natures” doctrine of the Dharma Characteristics (Hossō) school, which classifies sentient beings into five groups according to their inborn capacity, three of which it holds can never attain Buddhahood.