I've plunged right into the main text and swum towards content focuses on asceticism and mysticism, as these two concepts appears to lie at the heart of Weber's distinguishing analysis of religious communities. The main chapter in my particular edition of the Sociology of Religion (translated by Ephraim Fischoff and part of the series of 'Social Science Paperbacks') is Chapter XI: Asceticism, Mysticism and Salvation Religion. You should be able to find quotes conveniently via the book search in the Google Books rendering of 'Economy and Society' By Max Weber, so I'm dropping most of the page numbers.
Asceticism
Weber makes extensive use of "asceticism" - it's defined with very significant purpose for his works and probably because of this, as he concedes, the meaning doesn't have not the broadest usage.
He grounds many of his definitions in a salvific goal, detailed in chapter X: 'The Different Roads to Salvation,' which I find a reassuring basis for presenting religious practices at deeper levels. Thus, he then defines asceticism (in the penultimate paragraph): “Salvation may be viewed as the distinctive gift of active ethical behavior performed in the awareness that god directs this behavior, i.e., that the actor is an instrument of god. We shall designate this type of attitude toward salvation, which is characterized by a methodical procedure for achieving religious salvation, as "ascetic."” Weber indicates that for someone who leads a life without a keen focus on salvation: "The world is full of temptations ... more because it fosters in the religiously average person complacent self-sufficiency and self-righteousness in the fulfilment of common obligations."
Accordingly, the first words in chapter XI that introduce the general discussion on asceticism and mysticism are framed around the development of the path to salvation: “Concentration from the actual pursuit of salvation may entail a formal withdrawal from the "world"”. Weber contrasts between two constrasting modes or views concerning interaction in the world:
a) weltablehnende Askese ("world-rejecting asceticism"): One whose attitude is that participation in the wordly activities may be regarded as an acceptance of these affairs, "leading to an alienation from God."
b) inner-weltliche Askese ("inner-worldly asceticism"): a path of salvation that requires "participation within the institutions of the world but in opposition to them" according to the individual's own sacred religious dispositions and his qualifications "as the elect instrument of god." (Note that here "inner" qualifies worldly in the general sense of "world" - it's not referring to an individual's personal internal world. )
Wordly Asceticism
So Weber has defined "asceticism" using the world as a reference point and has defined two points of view. In the following pages he gives quite a number of examples, but they all seem related to inner-weltliche Askese, so I find it difficult to ascertain what is meant by weltablehnende Askese. It's meaning only becomes clearer when he contrasts it later with mysticism.
Characteristic of the inner-worldy ascetic type is the reformer/revolutionary: "he may have the obligation to transform the world in accordance with his ascetic ideals." Weber establishes the context in examples, including the 'Parliament of Saints' under Oliver Cromwell, who ruled with a strong puritan conviction (see e.g. Sir Charles Firth, Oliver Cromwell and the Rule of the Puritans in England); and the Quaker State of Pennysylvania "and in other types of radically pietistic conventile communism." I'm mot sure what to make of the latter (probably because my knowledge of the relevant history is not extensive).
Weber highlights inequalities: "such a congery of ascetics always tends to become an aristocratic, exclusive organisation within or definitely outside the world of the average people who surround these ascetics." Yet isn't that inappropriate regarding the organisation of the Quakers? Quakers are egalitarian - there is no church hierarchy as such. (see e.g. Facts About Friends by Ted Hoare on the Religious Society of Friends Website); and their meeting houses welcome people from outside for many kinds of activities. Pennsylvania is known for its religious tolerance, following William Penn's 'FRAME OF GOVERNMENT OF PENNSYLVANIA' (1682) allowing freedom of conscience:
For rulers are not a terror to good works, but to evil: wilt thou then not be afraid of the power? do that which is good, and thou shalt have praise of the same." "He is the minister of God to thee for good." "Wherefore ye must needs be subject, not only for wrath, but for conscience sake."
Weber's interest is directly on the institutions - the collective involvement reflecting religious beliefs and having started with two basic views of asceticism, focuses further on the second option of world involvement; following on from forced religiosity (as may be considered under the Parliament of the Saints) he considers the case of not demanding religious conformance.... and the tension between the world being both a divine creation and full of sinfulness(pp. 167-168) and hence argues for the necessity of careful involvement according to a strict legal code. Hence, it is argued, for Protestantism the importance of loyalty to obligations. Weber claims "it is the sole method of proving religious merit" and it's easy to see that where the legal has something to say about work and financial management, that can lead to the storing of capital...
In summary, Weber writes: "the person who lives as a worldly ascetic is a rationalist, not only in the sense that he rationally systematizes his own personal patterning of life, but also in his rejection of everything that is ethically irrational, esthetic, or dependent upon his own emotional reactions to the world and its institutions."
Mysticism
Mysticism? There may be a problem with this word - as a detractor first quipped long ago: "myst-i-cism begins with mist, puts the I in the centre, and ends in schism." I once read a meditation manual that had a forthright statement as if in protest at its sense of vagueness and impenetrability, saying that this was not a book where one would find mysticism, but rather it was about developing keen insight! Yet, in practice it's a term that reflects the deeper contemplative life that is not immediately accessible to the everyday mind and so the way of a 'msytic' may appear at first glance a complete mystery.
To try and get a handle on Weber's view of mystics I turned to the index and worked forwards from the first entry. Overall, I find it difficult to pin down definitions, because it seems that Weber tries to develop in parallel multiple strands interwoven around a few themes. There's a lot of movement across cultures and traditions, a lot is implicit and perhaps biased to a culture that is no longer so evident, so definitions don't stand out very clearly, but rather seem to emerge gradually along the way, tied to the themes that themselves are emerging.
First reference appears to be on page 119, which is in a chapter entitled 'Intellectuals, Intellectualism and the history of religion.' However, it only describes an influence through the various writings of those with monastic orientation (Buddhist, Islamic and medieval Christianity] - particularly poets, about which Weber remarks: "This circumstance also accounts for the psychological proximity of mystical and spiritual emotion to poetic afflatus, and for the role of the mystic in the poetry of both the Orient and the Occident."
Subsequent references are concerned with involvement of intellectual classes, how intellectuals turned against the papacy, a period during which "Humanists displayed ... an individualistic mysticism, as in Germany during the first period." [I couldn't find a name, but from a quick search online I come across Johann Reuchlin, who was interested in Jewish Mysticism]. Throughout Weber displays considerable knowledge of classical history and literature.
It's really only in the chapter 'The Different Roads to Salvation' that I gain some idea. He builds up to it by a consideration of ritual, noting that "salvation may be the accomplishment of the individual himself without any assistance on the part of supernatural powers, e.g. in ancient Buddhism." (Buddhism certainly has been described as salvation without a saviour). For Weber the purpose of ritual is to bring about a "religious mood" as "an instrument of the divine", whence the rituals themselves become superfluous. Weber describes how the deepening of this practice can lead to pietistic devotion so that it becomes continuous and readily takes on a mystical character, but remarks that it often lapses into pure ritualism. There's a lot of discussion of rituals, religious moods, systematisation with particular attention to educational aspects and how that can lend itself to greater involvement in society (e.g. training in casuistry in Judaism).
Weber then starts to draw out some features "out of the unlimited variety of subjective conditions" where certain methodological procedures of sanctification are of central importance "not only because they represent psycho-physical states of extraordinary quality, but because they also appear to provide a secure and continuous possession of the distinctive religious acquirement. This is the assurance of grace (certitudo salutis, perseverantia gratia)." And these "May be characterised by more mystical or actively ethical coloration" He goes on to list a number of practices to be adopted (over transient sense-based practices): "principally by planned reductions of bodily functioning, such as can be achieved by continuous malnutrition, sexual abstinence, regulation of respiration and the like." (These prompts me to think especially of the group of the world-rejecting lifestyle followed by the 5 ascetics that accompanied the Bodhisattva Gotama until he went off to finally attain nibbana by himself: apart from sexual abstinence, these are not aspects of the Buddhist path, a middle way that would not seek malnutrition or to regulate the breath.)
Then Weber gives some examples of mind training, through concentration methods. He observes that these practices may be further streamlined (p.162):
"Similarly the monastic procedural plan for attaining sanctification developed increasingly in the direction of rationalization, culminating in India in the salvation methodology of ancient Buddhism and in the Occident in the Jesuit monastic order which exerted the greatest historical influence."
Thus a combined physical /psychological regimen with regulation of manners and scope of thought and action. [An interesting link between Buddhist practice and Jesuit practice].
Weber approaches a definition really only towards the end of the chapter by once again using salvation as the anchor: "But the distinctive content of salvation may not be an active quality of conduct, that is, an awareness of having executed the divine will; it may instead be a subjective condition of a distinctive kind, the most notable form of which is mystic illumination."
So the salvific content is without reference to the world. It seems quite fitting in terms of Buddhist goal of nibbana - where the grounding is not in the conditioned, but the unconditioned. Yet, even Englightened beings before they attain to parinibbana have to walk on the Earth, breathe its air etc, i.e. there is conduct w.r.t. to the world and the quality of conduct is important - so for someone on the path, activity tends to good kamma and ideally to kiriya - and to describe this conduct for non-theistic religions or at least those religions where divinity is not central, one might be able to substitute simply: "having acted in a holy way."
And what is the quality of the conduct of these practitioners? "... and among them only as the end product of the systematic execution of a distinctive type of activity, namely contemplation." I initially had difficulty scanning the first few words of this sentence and thus making sense of it, but found a clearer translation by Stephen Kalberg (which can be gleaned from a Google search, so you don't need to actually read the article) : "... only to be achieved as the end product ...". So even mystic illumination is to be achieved and not in a random way, but systematically.
Who can undertake this practice? Weber claims it is restricted to a minority with religious qualifications. Yet the contemplative path is fulfilled today by the practice of meditation according to the Buddha's teachings and that is arguably open very widely. In fact I've been taught that there are only three kinds of peope who can't meditate: dead people, people who are severely mentally deranged and people who just won't try!
What more does Weber say about mysticism? Weber makes clear then need for cessation of mental involvement in worldly concerns: "For the activity of contemplation to succeed in achieving its goal of mystic illumination, the extrusion of all everyday mundane interests is always required." and "According to the experience of the Quakers, God can speak within one's soul only when the creaturely element in man is altogether silent." He asserts further, "In agreement with this notion, if not with these very words, it all contemplative mysticism from Lao Tzu and the Buddha up to Tauler." Yes, I think quietude is universal for the contemplative, though I think it important to emphasize that there's inevitably some conduct in the world and that conduct can (always) be used as part of the holy life, else the impression can be given that the mystical life is exclusively about cultivating jhanic absorptions, say.
Mysticism vs asceticism
So having depicted the mystic contemplative, Weber then draws a distinction with world-rejecting asceticism: “Such a contemplative flight from the world, characteristic of ancient Buddhism and to some degree characteristic of all Asiatic and Near Eastern forms of salvation, sems to resemble the ascetic world view - but it is necessary to make a very clear distinction between the two. In the sense employed here, "world-rejecting asceticism" is primarily oriented to activity within the world.” I'm still not sure about the meaning - but (looking at some articles elsewhere) I think for Weber it means that one moves in the world, particularly earns a living there, without trying to change the world. On the other hand, the mystic contemplative leaves behind such society. (However, it seems more logical to me to say that any interaction in the 'world experiment' is going to have some effects, possibly negligible).
Hence "in contrast to asceticsm, contemplation is the primarily the quest to achieve rest in god and in him alone." Weber adds some fair descriptions of some mental states characteristic of this path: "It entails inactivity, and in its most consistent form it entails cessation of thought, the nemesis of everything that in any way reminds one of the world."
Although the Buddhist path is to minimise distractions, the issue of the rejection of the world needs care, I think. It is most commonly a personal statement of an individual who resolves with great determination to go from being a householder into homeless life - an example, roughly contemporary to Weber is Ven. Sunlun Sayadaw. However, a general application of an 'anti-' tone is questionable, and may not be consistent with the Buddhist practise of the Middle Way and accumulating perfections (paramis), which necessarily has to take place in the world. From a Buddhist perspective, there are many inaccuracies or problems with language in the descriptions: "By these paths the mystic achieves that subjective condition which may be enjoyed as the possession of, or mystical union with, the divine." The nearest to "the divine" would be considered to be Brahma and hence it's more accurately a description of Brahmanism, not Buddhism which teaches this as anatta (not-self).
Generally, Weber writes in a way that seeks to be fair and representative, but "This is a distinctive organisation of the emotions which seems to promise a certain type of knowledge." appears a weak description! What kind of knowledge? Evidently mystical! "...although it becomes more incommunicable the more strongly it is characterized by idiosyncratic content, it is nevertheless recognised as knowledge." Weber uses the term "gnosis" giving rise to a new orientation to the world. [The 'idiosyncratic' is a term relative to the mundane, of course; conversely, using the transcendent as a frame of reference, the worldly life may be considered idiosyncratic too.]
Weber's view of Buddhist formulations: "In Buddhism, no one becomes one of the illuminated by explicitly affirming the obviously highly trivial formulations of the central Buddhist dogma, or even by achieving a penetrating understanding of the central dogma." Highly trivial?! Weber goes on to indicate the requirements of following "procedures for winning salvation.", i.e. Magga (path). Fair enough.
For Weber, "we are not interested here in the details of the general problem [of communication of this knowledge], but only in the negative effect upon behavior which is distinctive of all contemplation." Weber often associates the word "negative" with the contemplative because of their stance of fleeing from the world, it is a is relative perspective w.r.t. to social and economic involvement. Weber carries on piling up a lot of negative language, depicting a sharply divided contrast between 'the ascetic' and 'the contemplative,' a dichotomy with opposing views about the path to salvation and, e.g. "the contemplation of the mystic appears to the ascetic as indolent, religiously sterile, and ascetically reprehensible self-indulgence ...". I wonder, though, if this rather heavy and forced view of negativity might prove erroneous. Surely these differences don't have to have such negative associations - a SammaSamBuddha teaches for the benefit of others, whereas a Pacceka Buddha doesn't teach - yet in the Buddhist view both are worthy of praise as having attained to nibbana and never self-indulgent.
In relation to sustenance, Weber speaks through his perceived ascetic view that "the mystic lives in everlasting inconsistency, since by reason of the very fact that he is alive he must inevitably provide for the maintenance of his own life." And goes on to argue that to be consistent a mystic must maintain his life only by voluntary donation "it accounts for the very strict prohibition (... found among the Buddhists) against receiving anything that has not been given freely." Weber asserts on the next page: "It will be recalled that the central and almost sole lay virtue among the Buddhists was originally the veneration of the monks..." (echoing what he says in Chapter XI: The Social Psychology of World Religions in Max Weber: Essays in Sociology' by By Max Weber, H. H. Gerth, C. Wright Mills: "Buddhism was propagated by strictly contemplative, mendicant monks, who rejected the world and, having no homes, migrated. Only these were full members of the religious community; all others remained religious laymen of inferior value: objects, not subjects, of religiosity.")
I really think there's a lot that can be contested in what Weber says here, not least whether his understanding of the ascetic view is truly reflective. Regarding the assertion that the Buddhist monastic "lives in everlasting inconsistency": if considering the Thai Sangha, for example, the negative associations with lay people is not a very accurate depiction except perhaps for a very small minority of dhutanga bhikkhus roaming forests. In practice the relationship between lay and ordained is not one of antipathy, but rather there is a veritable positive eco-system between Sangha and lay supporters - a relationship in which the lay community provides conditions amenable to progress for all, especially monks, yes, but also for each other; and traditionally this includes education and medical help administered by the Sangha to the lay people and encouragement along the Buddhist path.
Furthermore, the lay supporters themselves can share in the practice - they too are expected to cultivate dana, sila and samadhi, albeit less intensively; in the Buddha's time, these were formally upasikas and upasakas, two of the four groups commonly addressed by the Buddha as being his disciples. In Thailand, although most teachers are members of the Sangha, there are some very highly respected lay teachers (and not just the anagarika nuns) - indeed my mother's main meditation teacher, Ajahn Gaew, as a lay person instructed a group of bhikkhus because he was an advanced practitioner. And, I'm quite sure this is not just contemporary, but was true at the time of the Buddha - as argued amply by Jeffrey Samuels, especially concerning attainments along the path to enlightenment, in 'Views of Householders and Lay Disciples in the Sutta Pitaka: A Reconsideration of the Lay/Monastic Opposition', Religion, Volume 29, Issue 3, July 1999, Pages 231-241.
Weber goes on to express more curious views about Buddhism (p.171): "in any case Buddhism enjoined the avoidance of every type of rational, purposive activity, which it regarded as the most dangerous form of secularisation." This needs unpacking as I'm not sure what Weber means, but it sounds mistaken. A monk repairs his kuti in order to help with his practice during the rains retreat. That sounds rational and purposive activity to me!
Conclusion
Overall, I find it encouraging that Weber has tried to understand individual motivations at a deep spiritual level and his work has many interesting ideas flowing from this. However, from what I've read so far, I sense that whilst he has a good command of European history and thought, his analysis of at least Oriental religion contains contains too many misconceptions, which I suspect are based on preconceptions arising out of his own European conditioning. Perhaps further study, under an appropriate guide, will clarify what Weber is trying to say, the main points to be understood, but at the moment it reduces my confidence in the validity of his arguments (and subsequent conclusions).