Q:

Seeing deleted comments

I just had a moderator delete some comments of mine, due to the extended discussion nature of them, on Can I always use butter instead of margarine when baking?,  however I had assumed that I (at least) could see the deleted comments that I spent a lot of time constructing, to make specific points, well. 
Please tell me that there is a way of seeing / getting a copy of them? 

A:

I'll post a copy here for posterity, and to explain why I deleted them.  But I absolutely stand by my position that they don't add value to the question or answer.   I appreciate that you spent a lot of time writing them, but that unfortunately doesn't make them relevant to future readers. 
Here are the original comments I deleted:

@SAJ14SAJ - Think it would have been/be great to cite your source, which can be done by follow up comment, or copy+delete+paste into new comment below. –  user66001 2 days ago
  deleted by Jefromi♦ 18 mins ago undelete
@user66001 You can easily locate it by googling "USDA standard of identity margerine".  However this fact is sufficiently well known, and my reputation sufficiently established on this site that I feel no need to make a citation. –  SAJ14SAJ 2 days ago
  deleted by Jefromi♦ 18 mins ago undelete
@SAJ14SAJ - I find your stance interesting for several reasons - 1) You seem to wish to debunk another's opinion.  Not knowing you, and not having a 3rd parties information, I am not sure who most people would believe; 2) In terms of your reputation - I am relatively new to this StackExchange subsite, and as this is a publically available site/page am sure that there are a fair few others that are unfamiliar with your activity on this site too; 3) As to "sufficiently well known", I am new to this country, so (as can be guessed) this doesn't apply to me, and perhaps some others. –  user66001 1 hour ago
  deleted by Jefromi♦ 18 mins ago undelete
3) You not citing your sources, is causing multitudes more people's time (hopefully) finding (hopefully) the same/similar info that supports your stance; 4) If I could find on your information by Google (Decreasingly my first attempt to find the info, but after your response, on cooking subjects, maybe how often I use google will increase), presumably we wouldn't need the great Q&A sites that comprise the StackExchange system. –  user66001 1 hour ago
  deleted by Jefromi♦ 18 mins ago undelete
For me, I have for a while now dismissed people's opinions that I don't know to be true/false, that are without citations, by default (There is just too many people, with too many opinions to spend the time fact checking all of them).  I also feel, and practice, the opinion that it is the responsibility of those providing information, to provide more than just their words (Maybe it is the scientific view I have on the world).  P.S I apologize about the suggestion of how to cite (Should have checked your rep first). –  user66001 1 hour ago
  deleted by Jefromi♦ 18 mins ago undelete
Anyways, for those who would find it useful, I google'd I believe this is a source that SAJ14SAJ may see fit to include, given it agrees with his stance. –  user66001 1 hour ago
  deleted by Jefromi♦ 17 mins ago undelete
If I had provided that information in an answer I would have linked the citation; this was a comment.  As to "debunking an opinion": no.  This is a fact.  It is either true or false, and not a matter of opinion. –  SAJ14SAJ 1 hour ago
  deleted by Jefromi♦ 17 mins ago undelete
How is one supposed to know that your comment is fact, instead of the answer's "fact"?  Also, I appreciate the distinction of answer vs. comment, but both can contain information that I feel should be cited.  To wrap this up though, as I don't feel we will agree on this subject, it was just a suggestion.  Thanks for your time :) – user66001 1 hour ago
  deleted by Jefromi♦ 17 mins ago undelete

And here are the follow-up ones I'll delete momentarily:

@user66001 I'm going to delete all the unnecessary discussion here.  Providing sources is always nice, and asking for one for a dubious claim is fine (though this one was indeed essentially common knowledge), but comments are not meant for extended discussion and definitely not for pointless arguments. –  Jefromi♦ 21 mins ago edit 
@Jefromi - That is really quite annoying, given the time to write them up, and the most-valid points I feel I have provided for a while (I am not the kind of person to pick (what I feel are) pointless arguments - Don't have the time), but understand your reasoning for the action (Pity there is not a way to hide these comments, and show them to people "on request"), and appreciate you keeping the information above for others benefit. –  user66001 11 mins ago  
@user66001 All that needed to be said was "could you provide a source".  If you want to discuss in depth, please ask a question if appropriate, or else talk in Seasoned Advice Chat.  If it's an issue with determining the appropriate way to use the site, please ask a question on Seasoned Advice Meta.  And comments are designed to be temporary - anything truly important to record for posterity should be in a question or answer.  The debate here did not fall into that category; it just made it harder for people to find the marginally relevant information below. –  Jefromi♦ 6 mins ago  
@Jefromi - I guess we also disagree how important is to seperate person A's information from person B's, regardless of the source of this information.  I felt the debate was relevant to the lack of a source (Which I did suggest), but also to the principle for others who may change their behaviour after reading the discussion.  Perhaps next time, moderators can move it into a chat session, so one presumably doesn't have to recraft their points again.  Lastly, I wasn't aware that comments were temporary, given how long some of mine have remained "attached" to their relevant question/answers. –  user66001 33 secs ago  

The question here is about substituting butter for margarine.  SAJ14SAJ pointed out something about fat content, and you asked for a source.  That's fine (though I wouldn't have felt the need to ask for a source).  And the follow-ups posting a source are fine as well - they provide a small amount of clarification.  But all the intervening discussion, all else aside, is definitely not about butter and margarine.  It's a discussion about how the site works, what you and SAJ14SAJ thought about what the other was saying, and so on.  It has no bearing on the question. 
We even delete answers which don't answer the question; comments, since they're already meant to be temporary, definitely can and should get deleted for the same reasons.  These comments obviously fall into that category.  If the discussion had been unresolved, I would have left them for the time being, but it was all taken care of - a source was found.  There's absolutely no need to show all future readers exactly how that result was arrived at.  Look up there - that's an awful lot to wade through to get to the link at the bottom to FDA regulations! 
If you ever feel that something's not being done right on the main site, and want to have a meta discussion like the one you had on that answer, you've found the place for it - meta.  It makes it public, obvious to those who care to see it, permanent, lets everyone vote on things, and so on.  Commenting, on the other hand, is a good way to add noise to a question or answer, so off-topic discussion gets deleted as it was here. 
Finally, I'll also note that, as I was deleting these, another user flagged the comments, quite correctly suggesting they be cleaned up. 
And a small digression, since you implicitly asked: topical, helpful comments do get left around.  When we say they're temporary, we really mean they're potentially temporary - if for any reason they're not needed anymore, poof, they're gone.  We're a bit lenient about it in general; I think we mods generally only delete things when they're painfully obvious or when they get flagged.  We certainly won't delete comments which add topical information to a post.  Ideally, that information would get edited into the post where it's more obvious, but that of course doesn't always happen. 
And I just noticed you edited your last comment to mention migrating to chat.  The system automatically suggests doing that once comments get long enough (I'm actually surprised it hadn't suggested you do it, with a link to make it happen, given how many comments were there).  But moderators don't currently have the ability to manually do that - see this feature request.  But really, if the discussion is ongoing, you can just go to chat and keep having it.  And if it's resolved (the point at which a mod will delete it), honestly, a permanent archive of it in chat is just going to be a ghost room.  In all likelihood, no one's ever going to go back and re-read it.  I know you said you wanted your effort not to be deleted, but I really doubt you or SAJ14SAJ is going to come back to it a month from now.