In what is ascribed to be Verse 18, Book V of Marcus Aurelius' Mediations, Marcus writes:
 "Nothing happens to any man which he is not formed by nature to bear."
 "Nothing happens to anyone that he can't endure."
 "Nothing happens to anybody which he is not fitted by nature to bear."
 "Nothing can befall any man, which he is not capable by nature to bear"
In my further reading I found, (in Book X, Verse 3):
 "Everything which happens either happens in such wise as thou art formed by nature to bear it, or as thou art not formed by nature to bear it. If, then, it happens to thee in such way as thou art formed by nature to bear it, do not complain, but bear it as thou art formed by nature to bear it. But if it happens in such wise as thou art not formed by nature to bear it, do not complain, for it will perish after it has consumed thee. Remember, however, that thou art formed by nature to bear everything, with respect to which it depends on thy own opinion to make it endurable and tolerable, by thinking that it is either thy interest or thy duty to do this."
 "Everything that happens is either endurable or not. If it’s endurable, then endure it. Stop complaining. If it’s unendurable . . . then stop complaining. Your destruction will mean its end as well. Just remember you can endure anything your mind can make endurable, by treating it as in your interest to do so. In your interest, or in your nature. "
 "Whatsoever doth happen unto thee, thou art naturally by thy natural constitution either able, or not able to bear. If thou beest able, be not offended, but bear it according to thy natural constitution, or as nature hath enabled thee. If thou beest not able, be not offended. For it will soon make an end of thee, and itself, (whatsoever it be) at the same time end with thee. But remember, that whatsoever by the strength of opinion, grounded upon a certain apprehension of both true profit and duty, thou canst conceive tolerable; that thou art able to bear that by thy natural constitution."
My Queries are as follows:
Is the latter verse a product of Marcus' progression of stoic conceptions, the 1st verse later being regarded by him as a non-universal truth and requiring the qualifications he affirms in the 2nd Verse? Or do they convey fundamentally different meanings that I am not perceiving.
There is a specific section of Long's translation of the 2nd Verse that I do not understand: "Remember, however, that thou art formed by nature to bear everything, with respect to which it depends on thy own opinion to make it endurable and tolerable, by thinking that it is either thy interest or thy duty to do this.". When he states, "with respect to which", is "which" inferred to be "everything"? Does this mean Marcus intends not for the 1st verse to be interpreted in isolation, but with consideration of the succeeding qualifications (that he supplies in the 2nd Verse).
Gregory Hays seems to interpret the verse as being tautological in nature, that is: "you can endure anything your mind can make endurable", which does not elucidate on the threshold between those things endurable and not. Is this the correct of line of thinking?
3.1 And Casaubon similarly states "that whatsoever by the strength of opinion ... thou canst conceive tolerable; that thou art able to bear that by thy natural constitution." meaning that one's "strength of opinion" determines the threshold of endurability, and is what your "natural constitution" is able to endure, (constitution assumed to be: "a person's physical state as regards vitality, health, and strength." (def. 3, sense 1 of Lexico.) rather than "a person’s' character" def. 3, sense 2). Long differs in that he translates Marcus without reference to bodily fragility (natural constitution), and the verse as a whole seems to assume that, being a human is "formed by nature to bear everything", the body can match any form of pain endurance, without the inevitable threat of destruction imposed by those stimuli of pain, that in actuality, requires damage to the body ( E.g. Lopping an arm off). Is my interpretation flawed?
3.1.1 Could "everything" as Long translates Marcus, refer to the set of all things able to be borne, rather than the set of both things bearable and unbearable? in which case "formed by nature to bear everything" would be equivalent to "formed by nature too bear [the set of all things able to be borne", a tautology.
3.2 This might merely be signification of my ignorance of antiquated English but what does Casaubon mean by "true profit". Is this what Long and Hays translate as interest?
3.2.1 (More applicable to English.stack.exchange) What is the purpose syntactically of the square bracketed [that]: "thou canst conceive tolerable; that thou art able to bear [that] by thy natural constitution.". And, is Casaubon's translation more faithful to Marcus, as the clausal arrangements of the last sentence of the 2nd Verse are markedly different from those of Long or Hays' translations. This might be the source of my confusion as to the first part of question 3.2.1.
 https://en.wikiquote.org/wiki/Marcus_Aurelius#Book_V (Gregory Hays and Unknown respectively)
 http://files.libertyfund.org/files/2133/Aurelius_1464_LFeBk.pdf (Francis Hutcheson and James Moor)
 http://seinfeld.co/library/meditations.pdf (Gregory Hays)