Buddhas and Kami

[O]riginal enlightenment thought influenced a shift in how the unity of kami and Buddhas was understood. During the Nara and Heian
periods, the Buddhas and bodhisattvas, who transcend time and space, had increasingly come to be identified with specific local deities and thus grounded, as it were, in the temporal and geographical realities of Japan. The logic of these identifications was eventually expressed in terms of honji-suijaku, language borrowed from T’ien-t’ai/Tendai Lotus Sūtra exegesis. The Buddha of the latter fourteen chapters of the sūtra, or “origin teaching” (honmon), who attained enlightenment countless kalpas ago, is the Buddha in his original ground (honji), while the Buddha of the first fourteen chapters, or “trace teaching” (shakumon), is the “manifest trace” (suijaku) who appeared in this world as the historical Buddha. Chih-i had likened the relation of the two to that of the moon in the sky and its reflection on a pond. When this relation was applied to that of Buddhas and kami, it became possible to conceive of the deities, not merely as protectors of Buddhism or as suffering beings in need of Buddhist salvation, but as local manifestations of the transcendent Buddhas and bodhisattvas, compassionately projected as a “skillful means” to lead the people of Japan to enlightenment. (Page 41)

Original Enlightenment and the Transformation of Medieval Japanese Buddhism