Given here is an explicit statement of philosophos conduct/practice that could be added to a list of such surviving explicit "regulations" compiled from the extant written Platonist texts, from the Dialogs to the end of Platonism in antiquity, though so much appears to be lost or never committed to writing, though the Phaedo also enjoins voluntary monastic poverty, I think, pretty explicitly, and it is also at least implied, if not outright stated, in the Politea:
"O both dear Pan and how many other gods (are) here, give to me to become/be beautiful/noble inside: but how much I have outside to be friendly with the things inside for me. And may I consider the wise person rich: and may the quantity of gold for me be how much no one other than the one having control over sensual desires, the sane person, would be able to bear or manage/observe." (Phaedrus, 279 b9-c3)
The above is my own rendering, which may differ noticeably from other translations of the Phaedrus.
Here are a few other explicit statements for a list for a philosophos’ “rule” from some surviving fragments (all in my own quick, rough draft, off the cuff translations):
From Olympiodorus' commentary on the Phaedo:
" "The philosopher, as far as is not absolutely necessary, looks down upon/disdains the care of the body"...The are three (kinds of) activities: either natural and necessary, as taking nourishment and sleeping; or natural, but not necessary, as sexual intercourse; or neither natural nor necessary, as finery and how many things there are of variegated clothing--there being these three (kinds of) activities, therefore, the philosopher will have nothing at all to do with the natural but not necessary and the neither natural nor necessary, but will thrust them away from himself/reject/despise them (for nocturnal emissions will suffice for him in regard to secretion of semen), but he will make use of the first (i.e., the natural and necessary) a little bit perfunctorily/pro forma, as not to take his fill/make much of them. "If, then, these things are thus, the philosopher, as far as is not absolutely necessary, disdains the body; such a one is willing to die; the philosopher therefore practices death."..."
This is a clear and explicit statement that the Platonist philosophos is a celibate ascetic.
From Damascius' commentary on the Phaedo:
"...the contemplative philosopher is one wanting as his goal having been made one with the (hypostases) above himself and to be theirs rather than of himself: on which account (Plato) says "(it is not lawful) for the not pure to touch the pure".
It is necessary for the one being purified and hastening to be made like the Pure first to reject pleasures and pains as far as he is able; second, he must nourish himself with plain, simple food without luxury, but also food that is righteous and temperate (but this is untainted with blood and spotless) and that is holy and in accord with ancestral practice (for the food that is unholy and harming animals and coarsening the spirit makes the body intractable to the soul and unfit for contact with God); third, he must cut off the unharmonious wrong motion of the appetitive irrationality (for what would one standing aloof from all external things desire and with what would he be angry?), but if ever such a sort of thing would be moved either awake or asleep, it is most quickly put down by the reason; fourth, he must keep away from all sense-perceptions and imaginations, as far as it is not necessary to use them; fifth, the one wanting to be released from the multiplicity of becoming is to be separated from the opinions of all various sorts; the sixth precept out of all of them, is to escape the variegated complexity of thought and pursue the simpler expositions and distinctions with a view to becoming accustomed to the undivided intelligence."
This is an injunction to vegetarianism.
The Timaeus is explicitly vegan, as is the Epinomis.
Of course, Porphyry tells us in the "Life" that Plotinus "didn't abide to take medicines made from wild animals, saying that neither did he allow foods from the bodies of domesticated animals" and Porphyry, of course, wrote his whole book on the necessity of vegetarianism, and with it philosophical asceticism.
Though it is not directly from Platonism, but from Neo-Pythagoreanism, which is likely more derived from Platonism, in Philostratus' LIfe of Apollonius of Tyana, Apollonius is given as explicitly and in detail setting forth as necessary 'precepts' 'the big three': celibacy in all respects, vegetarianism and probably veganism (including not wearing leather, etc.), and teetotalling:
“For if someone has come to my standards of conduct, he would choose to get rid of all food (lit., how much of a table) of (i.e., coming from) animals; and he would utterly forget wine and not make turbid the vessel of wisdom that stands in the souls of those abstaining from wine; neither a cloak will warm him, nor wool, that has been shorn from an animal, and I give to him shoes of papyrus, and to lie down to sleep as it chances; and if I perceive him giving way to sexual desire and love, I have pits of perdition down into which Righteousness, the attendant of Wisdom, bears such people and thrusts them (into them)...”
I think that probably the above examples could be expanded and multiplied many times through searching the fragmentary surviving texts and probably there were many more such explicit prescriptions in the likely much greater bulk of Platonist literature that is lost to us (for example, because of the Muslims burning the great ancient library of Alexandria and the Christians burning whatever may have escaped the Muslims!), but just the above, with, of course, the Phaedo, Republic, and Timaeus and others, may perhaps be enough to obviate concern about any lack of structure or definite prescriptions in Platonism. It seems that the ascetic Path of Platonism is pretty clear, it's just that it is left to the individual, who is one of the few not the many and is presumed to have some spiritual discernment himself, to work out the exact details in each particular circumstance, without, for instance, the sort of long lists of silly, absurd, and neurotic details given in, for example, the Buddhist Vinayas and the sort of attempts criticized in the Republic to endlessly create detailed rules for every particular circumstance to try to make up for a lack of actual righteousness, renunciation, asceticism, and spiritual discernment and informed-ness and intelligence enabling the ascetic to decide more correctly what to do in each case in accordance with the actual principles of the contemplative ascetic life and practice and the single-minded striving for release and the telos without worldly concerns and desires.
I might make another suggestion of a resolution to feeling a want of a set of formal precepts or regulations for Platonist contemplative ascetics/philosophoi in the extant texts--in fact, a more really Platonist, perhaps, and ultimately more satisfactory and definitive solution. It is, though, one that is not necessarily easy to implement and hardly anyone now could do it or even try to do it. If one can manage to clearly and fully "see" or "touch" or "know" or come in contact with in contemplation, having ascended to the noetic realm, to the level of Nous, and entering into it, the actual Form/Idea of "contemplative-ascetic-in itself" or "contemplative-asceticism-in-itself" or "philosophos-in-itself" or "Platonist-renunciant/yogi-in-itself" or etc.--however, one might choose to label it just as a means of focussing on that one particular Form as it truly and really and paradigmatically exists in Nous--one will find that it contains in itself, is the higher source of, (in unity and interpenetration with the separate Forms of the individual virtues, etc.) all the practices/"precepts"/necessary prescriptions/standards of conduct/"regulations”, etc. that we talk about--celibacy, veganism, teetotaling, monastic poverty, abstaining from worldly entertainments, simplicity of food, drink, and clothing, world-renunciation, solitude, sitting in contemplation practice, etc., etc. All are there, though, of course, not in a series or list of statements in English(!) at the level of discursive thought, but as the actual really existing aspects of the complex level Form. After thoroughly contemplating this Form at the level of Nous, when the soul is not even really, in a sense, itself but has entered into a degree of unity with Nous, when the soul returns to this level the logoi corresponding to or emanating from the Form will appear clearly in the soul as the statements of necessary practice or conduct at the discursive verbal level. Hard for me to put the matter into words and a hard thing to do, but I think this is a much more ultimately satisfactory source of and point of reliance for, the real thing, what constitutes ascetic practice and conduct than feeling dependent on karmically appearing sensory experience, which is, after all, really what any text we have is. As Platonist contemplative ascetics, we have a great advantage and freedom in that our "regulations" of renunciant/ascetic conduct are eternally there and always accessible and real and unerring and not a matter of opinion in the realm of being, in the noetic realm, and we don't have to depend on karmically chancing to encounter teachings of such in the uncertain, always changing, impermanent, only the object of opinion not actual knowledge, sensory realm of becoming like practitioners of other systems. (And, ultimately, even further, our askesis comes from the source of all knowledge, the Good Itself, and direct contact and union with the Good will also, even more, upon the return, lead to all the logoi of contemplative ascetic practice being present at the discursive level in the soul.) All the prescriptions and ideas of ascetic practice that we read about in Platonist texts and/or in the texts of other systems can then serve as reminders to help the soul recollect the real ascetic standards that it once knew in itself and now recontacts or remembers or learns in contemplation. (The Platonist teaching of learning being recollection solves a multitude of difficulties!)
