Meaning of さもあろう


In _Mushibugyou_ there is this sentence:

> 実物の蟲もさもあろうというリアルな夢だな

The speaking character sees a giant mosquito (giant insects are common in the
setting), thinks to be in a dream, and that he says that sentence; while I
guess it means something along the lines of "It's a realistic dream, an insect
close to the real thing", I can't understand what もさもあろうという means; I tried
looking online and on my grammars, but while I found [some construction with
さも](https://hinative.com/questions/19945868), I'm not sure it's the same
thing, and how that construction works.




Yes, さもあろう is can be considered as a variant of さもあらん or さもありなん.

さ (然 in kanji) is an archaic equivalent of そう ("so", "this way") in modern
Japanese. も is a particle.

  * [Meaning of さすれば as a verb](https://japanese.stackexchange.com/q/43301/5010)

あろう is the "volitional form" of ある. A volitional form can have an inferential
meaning, although this usage is becoming old-fashioned.

  * [がな and ておろうな at the end of sentence parts](https://japanese.stackexchange.com/q/63091/5010)
  * [What does the volitional for do in this sentence: 今までリーゼには見せたことの無いであろう優しい目](https://japanese.stackexchange.com/q/53432/5010)
  * [Has Japanese syntax changed between the 1950s and today?](https://japanese.stackexchange.com/q/94644/5010)

> > 明日は雨が降りましょう。
>
> This was common in weather forecast until the 1970's, but we never hear this
> today.

なん in ありなん is explained in this question:

  * [What's な doing in 絶えなんとする?](https://japanese.stackexchange.com/q/92851/5010)

All in all, あるだろう, あろう, あらん and ありなん all have a similar meaning.

Practically,
[さもあらん](https://jisho.org/word/%E7%84%B6%E3%82%82%E3%81%82%E3%82%89%E3%82%93)
and
[さもありなん](https://jisho.org/word/%E7%84%B6%E3%82%82%E3%81%82%E3%82%8A%E3%81%AA%E3%82%93)
should be learned by rote as a set phrase without worrying about its archaic
grammar. さもあろう is not really a common set phrase, so you have to get used to
the inferential usage of the (よ)う-form, which is a little old but still part
of the modern grammar.




Yes, さもあろう is can be considered as a variant of さもあらん or さもありなん.

さ (然 in kanji) is an archaic equivalent of そう ("so", "this way") in modern
Japanese. も is a particle.

  * [Meaning of さすれば as a verb](https://japanese.stackexchange.com/q/43301/5010)

あろう is the "volitional form" of ある. A volitional form can have an inferential
meaning, although this usage is becoming old-fashioned.

  * [がな and ておろうな at the end of sentence parts](https://japanese.stackexchange.com/q/63091/5010)
  * [What does the volitional for do in this sentence: 今までリーゼには見せたことの無いであろう優しい目](https://japanese.stackexchange.com/q/53432/5010)
  * [Has Japanese syntax changed between the 1950s and today?](https://japanese.stackexchange.com/q/94644/5010)

> > 明日は雨が降りましょう。
>
> This was common in weather forecast until the 1970's, but we never hear this
> today.

なん in ありなん is explained in this question:

  * [What's な doing in 絶えなんとする?](https://japanese.stackexchange.com/q/92851/5010)

All in all, あるだろう, あろう, あらん and ありなん all have a similar meaning.

Practically,
[さもあらん](https://jisho.org/word/%E7%84%B6%E3%82%82%E3%81%82%E3%82%89%E3%82%93)
and
[さもありなん](https://jisho.org/word/%E7%84%B6%E3%82%82%E3%81%82%E3%82%8A%E3%81%AA%E3%82%93)
should be learned by rote as a set phrase without worrying about its archaic
grammar. さもあろう is not really a common set phrase, so you have to get used to
the inferential usage of the (よ)う-form, which is a little old but still part
of the modern grammar.

