There is no doubt that the Buddhaʼs selflessness (anātman) theory was a reaction against the Upaniṡadic ātman philosophy, but the question which particular ātman doctrine he had in mind is still left unsolved. This paper attempts to point out intimate relations between the Buddha and Uddālaka Āruṅi. According to the ChāndogyaUpaniṡad (Chapter VI), Uddālaka expounded the philosophy of Being (sat), denying the non-being (asat) theory. From Being the three principles (light, water and food) were produced. Then Being entered in to them as living self (jīvaātaman) and developed ʻname and formʼ (nāma-rūpa). The product is described as a transformation (vikāra) which is grasped by means of words, a name (vācārambhaṅaṁ vikāro nāmadheyam), because it does not differ substantially from the three principles. According to Uddālaka the order of language must coincide with the order of the phenomenal world. When the Buddha criticized Sañjayaʼs doctrine as committing the error of vācāvikkhepa, he must have in mind Uddālakaʼs theory o f the language (omitting the details of the ontological background). Being and non-being are important points of dispute criticized by the Buddha, i. e. sassatavāda and ucchedavāda. According to Uddālakaʼs way of thinking the negation of being is equal to non-being, and the negation of non-being is equal to being. In order to deny Uddālakaʼs Being, the Buddha devised the compound
ʻsakkāyaʼ (sat-kāya) found in the Suttanipāta. The meaning of this word can 仏教とウッダーラカの哲学（今西) 19― 224 ―be very clearly realized. But later the compound sakkāyadiṫṫhi became current, and the original meaning of sat was forgotten. Here we could also add that the paṫiccasamuppāda (pratītyasamutpāda) theory also denies both being and non-being. According to the traditional accounts Sāriputta, Sañjayaʼs disciple, heard Assaji reciting a verse on paṫiccasamuppāda and converted immediately to Buddhism. The episode can be said toencapsulate the symbolic moment of the Buddhaʼs making his appearance on the stage of Indian philosophy.
