What is the historical basis for the buddhas examples of "wrong livelihood"?

Question

One of the recurring themes in the teachings of the buddha is the noble eightfold path; the basis for achieving nibbana. Oftentimes the components of it are presented as their "wrong" counterparts, and usually a row of examples is provided for what some instances of those "wrong" counterparts are. I am specifically curious about what kind of practical basis (as many of the teachings have some) the instances of "wrong livelihood" might have, with regard to the historical context of when the teachings were formed.

In DN.10. "Subhasutta—Bhikkhu Sujato" the following phrase can be found: (emphasis mine)

There are some ascetics and brahmins who, while enjoying food given in faith, still earn a living by unworthy branches of knowledge, by wrong livelihood. This includes rites for propitiation, for granting wishes, for ghosts, for the earth, for rain, for property settlement, and for preparing and consecrating house sites, and rites involving rinsing and bathing, and oblations. It also includes administering emetics, purgatives, expectorants, and phlegmagogues; administering ear-oils, eye restoratives, nasal medicine, ointments, and counter-ointments; surgery with needle and scalpel, treating children, prescribing root medicines, and binding on herbs. They refrain from such unworthy branches of knowledge, such wrong livelihood. … This pertains to their ethics.

Some of these are easily explained, such as performing mystical rites for luck and blessing, but the examples of medical practice and administering "...nasal medicine, ointments..." leave me somewhat confused. What could be a historical reason for why these practices are considered "wrong livelihood", and more generally, what is the core traits that define "wrong livelihood"?

Answer 1

The examples in my quoted passage appear pretty specific and related in some way.

I expect these were some of the ways in which "holy men" might "make a living" -- i.e. practicing mystical rites, fortune-telling, and medicine.

The Buddhist Monastic Code I: The Patimokkha Training Rules Translated and Explained says,

... includes such practices as:

1. running messages and errands for kings, ministers of state, householders, etc. A modern example would be participating in political campaigns.
2. scheming, talking, hinting, belittling others for the sake of material gain, pursuing gain with gain (giving items of small value in hopes of receiving items of larger value in return, making investments in hopes of profit, offering material incentives to those who make donations). (For a full discussion of these practices, see Visuddhimagga I.61-82.)
3. Practicing worldly arts, e.g., medicine, fortune telling, astrology, exorcism, reciting charms, casting spells, performing ceremonies to counteract the influence of the stars, determining propitious sites, setting auspicious dates (for weddings, etc.), interpreting oracles, auguries, or dreams, or—in the words of the Vibhaṅga to the the bhikkhunīs’ Pc 49 & 50—engaging in any art that is “external and unconnected with the goal.” The Cullavagga (V.33.2) imposes a dukkaṭa on studying and teaching worldly arts or hedonist doctrines (lokāyata). (For extensive lists of worldly arts, see the passage from DN 2 quoted in BMC2, Chapter 10. For the connection between lokāyata and hedonism (e.g., the Kāma Sūtra), see Warder, Outline of Indian Philosophy, pp. 38-39.)

Monks are allowed to practice medicine but for each other, not for laypeople and not for "livelihood".

There's a more extensive list of what's not considered Right Livelihood for monks on pages 773 through 778.

I expect there is (at least sometimes) a historical basis for each rule: my impression is that the Vinaya rules were formulated as needed -- i.e. when someone did something wrong, the Buddha said "don't do that", and that became a new rule -- and that Vinaya's commentary includes the "origin stories" for the various rules (but I'm not sure that the Vinaya's commentary has been translated).

Answer 2

The quoted passage refers to wrong livelihood for monks, but not necessarily for lay persons. You can find more such descriptions in DN 2.

This is because a monk is meant to be a professional practitioner of the Dhamma (Buddha's teachings), concentrating on study of scripture, contemplation, meditation and teaching of the Dhamma.

Wrong livelihood for lay persons can be found in the sutta quote below:

"Monks, a lay follower should not engage in five types of business. Which five? Business in weapons, business in human beings, business in meat, business in intoxicants, and business in poison.

"These are the five types of business that a lay follower should not engage in."
AN 5.177