Oh noes! A point of grammar I do not fully understand.

[The Man who was Thursday]

Take the sentence "May the Lord smile and the Devil have mercy."

Should there be a comma before the "and"?

And don't just randomly guess, please. I want sources.  

[Caleb Hellforge]

'The Devil have mercy.' cannot seem to become its own independent clause, so I would say no.  

[The Man who was Thursday]

Vadatajs

'The Devil have mercy.' cannot seem to become its own independent clause, so I would say no.

The auxiliary verb for both clauses is the same, so it's merged into one.

Also, that distinction doesn't work in a situation like so:

"May the cheese be fresh and the crackers have flavour."  

[[ Pyrite ]]

Ezra Pound

And don't just randomly guess, please. I want sources.

[x]
Wait, you want us to go out and research this for you? Ah ha ha ha ha ha!!

~Pyrite
[x]  

[[Mammon]]

Ezra Pound

The auxiliary verb for both clauses is the same, so it's merged into one.

If that's the case then aren't they still two independent clauses joined by a coordinating conjunction? And if that's the case wouldn't that sentence fall under the standard rule for compound sentences (i.e. a comma before the "and" would be necessary)?

Reference:
http://www.ucalgary.ca/UofC/eduweb/grammar/course/sentence/2_5b.htm  

[The Man who was Thursday]

[ Pyrite ]

Ezra Pound

And don't just randomly guess, please. I want sources.

[x]
Wait, you want us to go out and research this for you? Ah ha ha ha ha ha!!

~Pyrite
[x]

I wouldn't be surprised if some people in a grammar guild have multiple grammar references already bookmarked.


@ [Mammon] -- Yes, probably, but it could also just be a list of two clauses, thus not needing a comma. This is what I think is happening, but I've never seen such a structure before.  

[Missy Wyvern]

I don't know the technical jargon (I don't usually pay attention in English 111), but it would appear to me that the sentence is only one complete thought without the need to be split.  

[MakanaVermillion]

Technically, it doesn't need one... but typically in English classes, a professor or teacher will say that a comma isn't required when you use "and." In some cases, a comma would be necessary, like:

"I like chocolate chip cookies, and Susan likes pickles."

Reasoning (from what I understand): That sentence can be broken into two coherent sentences.

Don't ask. It made more sense in my head. ninja  

[Ame Yuki Kaze]

I'd say there's no need for a comma because the sentence is said without a pause.  

[The Man who was Thursday]

I'm going to say there's no comma because it's a list of two clauses.

Curious, that.  

[play it loud]

The two clauses are of subjects that oppose one another and are directly linked through that, so the "and" acts as a pause itself.

I think... neutral