さくらさくらの「ぞ」はどういう意味？

Question

桜桜の歌詞で「匂いぞ出{い}ずる」と言った（どうやっていうの？）文があります。その文のぞはどういう意味ですか？助詞じゃないですか？

I don't really know how well I structured that. In any case, what is the functionality of ぞ in さくらさくら? I can only find web definitions for emphasis, at the end of sentences.

Answer 1

This 「ぞ」 is a 係助詞{かかりじょし} (binding particle) from classical Japanese.

History: It was originally そ in the Nara period, then ぞ in the Heian period, gone in the Muromachi period except for people intentionally trying to sound poetic, such as the author of this poem.

Semantics: It stresses/emphasizes what it marks

Syntax: It occurs in the usual spots of a 係助詞 (the syntactic class containing は, も, こそ, でも, etc.), but in addition, it is followed by the 連体形 of a verb -- this phenomena occurs with a few other 係助詞 in Classical Japanese and is called 係り結び.

Examples:

右近ぞ見知りたる。呼べ！
ukon zo misiritaru. yobe.
"Ukon knows for sure. Call her!"

みな鎧の袖をぞぬらしける。
mina yorohi no sode wo zo nurasikeru.
"Everyone wet the sleeves of their armor."

In your case:

霞か雲か　匂いぞ出{い}ずる
kasumi ka kumo ka nioi zo izuru
"Is it mist? Is it a cloud? The color radiates!"

(This 出ずる is in fact a newer spelling of the 連体形 of the 下二段活用動詞「出づ」, 「出づる」, meaning that this sentence fits the bill.)