During the time of the Buddha and before him the ultimate spiritual goal was to realize nibbāna in this life. Gotama also entered the houseless state to attain this goal. We have tried to reconstruct an outline of the entire spiritual journey of Gotama from isolated accounts scattered in the Nikāyas. Only those informations which can be reasonably accepted as historical and shown to have positively contributed to the attainment of the final goal have been studied in the present article. It appears that in an early phase of his spiritual Gotama controlled and cultivated his thoughts in such a way that the unwholesome thoughts ceased to arise while the wholesome thoughts continued to arise spontaneously. It is this type of mind──and not any god's pleading with him──that prompted him to preach the dhamma out of compassion for the suffering humanity. Nibbāna was accepted to be absolutely calm. One of the methods to develop mental calmness was to practice the four jhānas. Gotama also attained these jhānas and went beyond them moreover he remained unaffected by the mental state that arose after the 4th jhāna. Consequently he was free from the feelings of dukkha, sukha and adukkham-asukham, and developed greatly the calmness, mind fullness and concentration of mind. He ceased to take delight in and cling to any object. Thus he attained a special mental state which was perfectly concentrated, mindful and character rised by the absence of all these three feelings. It is noteworthy that this mental state came into existence without being intended. Gotama's wilful exertions were all directed only to eliminate agitative elements, and not to create a new mental state. Moreover as this mental state did not take delight in any object, it was free from all subjective influences in its functioning. Thus this was a unique mental state that had not got rid of the illusory ‘I’ and was devoid of wisdom regarding the nature of clinging etc., and yet was capable of absolutely objective observation. Observation made by this mental state was superior to any scientific observation which is always mixed up with the observer. With this special mental state Gotama realized ‘bodhi’, that is the wisdom about the destruction of the defilements（āsava, āśrava）, and the two other knowledges. This wisdom showed that one can transcends the conditioned and thus enabled him to deducethe existence of the unconditioned, the nibbāna. It destroyed the illusory ‘I’ and thus permanently uprooted clinging. A person who has realized ‘bodhi’ merges into nibbāna after the dissolution of the body. But the attainment of bodhi did not mark the end of Gotama's spiritual journey. Bodhi-mind was not utterly calm. He had yet no experience of nibbāna which is the supremely peaceful state. Moreover the attainment of ‘bodhi’ was not in conformity with the current śramaṇa tradition which valued only a mental state of calmness. Why, then, Gotama attained ‘bodhi’？ Without ‘bodhi’ the illusion of ‘I’ is not destroyed, so there always remains the possibility of falling away from a mental state. Moreover without bodhi nibbāna in this life cannot be attained. So Gotama first realized ‘bodhi’ and then went for the experience of nibbāna. Nibbāna is unconditioned and permanent. It is not possible to experience nibbāna as such , for anything mental is conditioned and impermanent. But the quality of utter calmness which is logically attributed to nibbāna can be experienced when all the saṁskāras（formative actions）cease and subside. Gotama attained this state with the realization of the cessation of perception and feeling （saññā-vedayita-nirodha） which is the same as the experience of nibbāna in this life. Gotama became the Tathāgata.
