It would seem that the key component of the message of major historical teachers such as the Buddha or Mahāvīra, at least as understood by its early transmitters, was not primarily a rational theory of the nature of the universe. It was rather the ideal of the renunciation of ordinary life and of the emotions, feelings, impulses, that tied one to it, a renunciation that also included a rejection of family, descendants and rebirth. At the centre was a conversion experience brought about through contact with a charismatic leader, and an ideal of a heroic struggle against the emotional entanglements and deep-seated volitional impulses of ordinary life, aimed at the achievement of a state of power, self-control an equanimity which is contrasted with the suffering and confusion of everyday life.
The key element was a reversal of everyday life such that the goal of liberation from rebirth came to be the centre around which their lives was now constructed. Following this reversal, the emotional entanglements of everyday life came to be seen as traps and obstacles to the achievement of that goal. Each tradition had its own specific set of techniques for how one then proceeded to actualize this vision.
The development of monasticism, in the sense of substantial communities of renunciates living together, seems to have taken place relatively quickly, and they were certainly well established by the time when the sutras and vinaya texts were written down in the second and first centuries BCE. The state support for Buddhism and the śramaṇa traditions at the time of Asoka would doubtless have provided the necessary conditions, even if this did not exist already.
In other words, the renunciate orders are unlikely to have developed until there were urban centres and trade between people from different localities. Indeed, the rise of ascetic orders followed the initial growth of cities: early Buddhism developed as a consequence of a changed situation, rather than of a rapidly changing one.
It is clear in any case that the new communities were from the beginning engaged with patrons and supporters in the cities, and were typically located close to them though not within them, in locations that were easily accessible to their populations. In anthropological terms, what was happening could best be described as a revitalization movement, a restructuring of modes of thinking and feeling, such as we see in many times of abrupt and radical change in human history and society.
The new social environment had the potential to create a new kind of self-awareness, particularly among people such as merchants, entrepreneurs, and government officials. It is possible that trade was mentioned ubiquitously in Buddhist literature not just because it was conspicuous in the society reflected in the texts, but because the actual development and expansion of Buddhism was so closely connected with it.
Indic religions, including Buddhists and Jainas as well as modern Brahmanical thinkers, have seen and still today see the ascetic as someone who renounces and rejects, above all, the claims and appeal of family life and of sexuality, and so of the society that is built upon the foundation of the life of the householder. Here the renouncer is implicitly figured male, while women routinely serve as representations of the family life to be renounced. Thus spiritual power, which is expressible through various this-worldly results, is derived from asceticism, while the normative mode of asceticism is carried out by males, and involves rejection the of, or at least conscious control over, sexuality.
Celibacy is associated with purity, and purity is undoubtedly seen as a valued state in Indian society. Sexuality, women and family life are all in various ways associated with impurity and pollution. It is clear that Hindu, Buddhist and Jain traditions are all uncomfortable with female ascetic practitioners, and none treats them as fully equal to men. This reflects the complex relationship between household a this-worldly-centred ritual and religious life, which is seen as a proper concern for women, ritual and religious life that is aimed at more transcendental and other-worldly goals, which is not so seen. We might think too of the iconography of young ascetic deities. It may be no accident that these are all celibate forms of deities who elsewhere are strongly associated both with male sexuality and with warriorship.
What is different in the Buddhist pattern, presumably, is the absence of the warrior role, and the stress on the ethical dimension of Buddhism, particularly on moral restraint, represented here above all by the sexual purity (i.e. celibacy) that is a central element of the definition of a Buddhist monk in contemporary Southeast Asian states. The idea of young men undergoing a temporary period as a Buddhist monk or in some other semi-ascetic role could be seen as a way of taking aggression and competitiveness and directing it inwards, into the quest of self-mastery. It is perhaps not surprising that the imagery of warriorship and victory that remain significant within Buddhism has occasionally expressed itself in real-life violence and war.
Reference: Geoffrey Samuel (2008), The Origins of Yoga and Tantra, Chapter 8, Asceticism and Celibacy, p. 173–190.