Lit. "mudra for turning the Dharma-wheel." A mudra or hand gesture *in 印 symbolizing the Buddha's turning of the Dharma-wheel, i.e. his preaching of the Dharma, or Buddhist law. It assumes a variety of forms: both hands, with the thumbs and forefingers joined, are held at chest-level with the left palm turned inward and the right palm turned outward (e.g. central deity of the *Amida 阿弥陀 pentad in relief *oshidashibutsu 押出仏 at Hōryūji 法隆寺); alternatively, the right hand, with the thumb and forefinger joined, is turned outward while the left hand, with the thumb and middle finger joined, is turned inward (e.g. mural of Amida in Hōryūji *Kondō 金堂).
In the Buddhist iconography of India, it is known as the Dharma-wheel mudra (Sk: dharmacakra-mudra) or mudra for setting the Dharma-wheel in motion (Sk: dharmacakrapravartana-mudra), and the Sino-Japanese term tenbōrin-in, also tenpōrin-in, is probably a translation of the latter. The prototype of this mudra, although not identical to it, appears already in Gandharan sculpture, and many fine examples dating from the Gupta dynasty may be seen at Sarnath. Sarnath was the site of the Buddha's first sermon, and the fact that images of *Shaka 釈迦 found here displayed this mudra was probably one of the reasons that this mudra took root as the symbol of the Buddha's preaching of the Dharma.
In Japan there are many examples of tathagata *nyorai 如来 images with this mudra dating from the Heian period and earlier, e.g. the aforementioned Hōryūji mural of Amida and the central deity of the *Taima mandara 当麻曼荼羅. There are also instances in which the fingers of the right hand are not bent (e.g. Shaka nyorai-zō 釈迦如来像 at Gangōji 願興寺, Gifu Prefecture), and since there are similar examples from Tang China (e.g. Metropolitan Museum of Art, New York), it is possible that they are the source of this finger position. At the same time, from the end of the Nara period onward, production began of many Tathagata images displaying a symmetrical tenbōrin-in with the palms of both hands turned outward and the thumbs joined with either the forefingers (e.g. Amida nyorai-zō 阿弥陀如来像 in Hōryūji Eden 絵殿), the middle fingers (e.g. Amida nyorai-zō, Hakkakuin 八角院, Kyoto), or the third fingers (e.g. Amida nyorai-zō in Kōryūji Kōdō 広隆寺講堂, Kyoto). The traditional asymmetrical tenbōrin-in, on the other hand, came to be referred to as the mudra of the auspiciousness of wisdom or chikichijō-in 智吉祥印 (e.g. Gōhō 杲宝; 1306-63, Dainichikyōsho ennōshō 大日経疏演奥鈔).
The tenbōrin-in is especially common in images of Amida predating the dissemination of the *mida-no-jōin 弥陀定印 in the mid- and late Heian period. According to the temple traditions of Saidaiji 西大寺, Nara, the image displaying the tenbōrin-in among the Four Buddhas *shibutsu 四仏 in its stupa and dating from the late Nara period, represents Hōshō 宝生 (Sk: Ratnasambhava), but today scholars consider it to represent Amida. The systematization of the different forms of the tenbōrin-in found in images of Amida gave birth to the following three types from among the mudras of the nine grades of Amida *Amida kubon-in 阿弥陀九品印): mudra of the upper grade, middle birth jōbon chūshō-in 上品中生印; mudra of the middle grade, middle birth chūbon chūshō-in 中品中生印; and mudra of the lower grade, middle birth gebon chūshō-in 下品中生印. It is, however, anachronous to apply these terms to images antedating the Edo period. This mudra is also occasionally used in certain versions of the *Taizōkai mandara 胎蔵界曼荼羅. Some scholars refer to this mudra as the *seppō-in 説法印, but since another mudra formed with only the right hand is also known by this name, it causes confusion if the same term is used as a synonym for the tenbōrin-in.