 Although Edo-period Buddhism was active in its scholarly productivity, its philosophical creativity did not match the activity of either Confucianism or Shintō, but there were exceptions. For example, Jiun Sonja (1718–1804) was a Shingon monk whose career ran counter to the typical pattern in Edo Japan in that he was first a Confucian and then became a Buddhist. Early in his career he enrolled in the Confucian academy of Itō Jinsai (1627–1705), where there was a strong emphasis on philology, on trueing up the key terms by scrutinizing the early Chinese texts. That inspired Jiun to investigate the roots of Buddhism, but in that case the relevant texts were in Sanskrit, a language barely studied in Japan at the time. Undaunted, he took up the study mainly on his own, becoming Japan’s premier authority on Sanskrit in the premodern period. Based on his research, Jiun argued for a new form of monasticism based on what he understood to be the original principles of Buddhism that preceded and transcended the various sectarian forms of Buddhism known in Japan. Thus, Jiun represents yet another example of an Edo-period thinker who used philology as a means of unearthing the origins and philosophical principles of a tradition—in his case Buddhism—in much the same way as his contemporaries did in Native and Confucian Studies.