observation of the mind ［観心］ ( kanjin): To perceive or awaken to the ultimate reality inherent in one’s life. Also, the method of practice that makes this possible. In contrast with doctrinal study of the Buddhist sutras, observation of the mind means to perceive in the depths of one’s being the truth that is beyond verbal explanation. Observing the mind is particularly stressed in T’ien-t’ai’s practice, in which meditation is focused on the true nature of the mind rather than upon some exterior object. In Great Concentration and Insight, T’ien-t’ai (538–597) taught meditation to perceive “the region of the unfathomable,” which is interpreted as either the unification of the three truths in a single mind or three thousand realms in a single moment of life. This means, in essence, to perceive one’s inherent Buddhahood, which is the goal of the T’ien-t’ai system of meditation.
  Nichiren (1222–1282) defined T’ien-t’ai’s observation of the mind as follows: “The observation of the mind means to observe one’s own mind and to find the Ten Worlds within it” (356). Nichikan, the twenty-sixth chief priest of Taiseki-ji temple, interpreted the above statement in his Exegesis on “The Object of Devotion for Observing the Mind” as follows: “‘To observe one’s own mind’ means to believe in the Gohonzon [the object of devotion in Nichiren’s teaching]. ‘To find the Ten Worlds within it’ means to chant [the daimoku of] the Mystic Law. If only you believe in the Gohonzon and chant the Mystic Law, then the Ten Worlds of the Gohonzon will become the Ten Worlds of your own life.” This interpretation is based on the passage from Nichiren’s Object of Devotion for Observing the Mind that reads: “Shakyamuni’s practices and the virtues he consequently attained are all contained within the five characters of Myoho-renge-kyo. If we believe in these five characters, we will naturally be granted the same benefits as he was” (365). In Nichiren’s teaching, the observation of the mind means to believe in the Gohonzon, the embodiment of three thousand realms in a single moment of life, and chant the daimoku. This is the teaching that embracing the Gohonzon is in itself observing one’s own mind, i.e., attaining enlightenment.
  Observation of the mind also means to interpret the sutras from the viewpoint of the truth one realizes in one’s life. In Nichiren’s teaching, it means to read the sutras from the viewpoint of the principle of Nam-myoho-renge-kyo.