曲がりくねった道
地図さえない
それもまた 人生
In this beautiful song from Misora Hibari, I don't understand the last line.
It surely means something like "That is life" but I don't understand the use of も and また. Why not saying それ人生? (I know, it couldn't fit in the song, but still from a grammatical point of view.)
By saying もまた (=also), the lyrics imply such a way of living (ie. "でこぼこ道や 曲がりくねった道 地図さえない") is not the only way of human life.
If you said それが人生 ("That is life") here, it would mean everyone lives a life with many ups and downs. It would be perfectly fine in the lyrics of other songs. However, the person in this song is not talking about people's life in general. She is recalling her own life, which she thinks was particularly turbulent but satisfactory.
それ人生 is broken. We sometimes drop が after それ in most casual and colloquial situations, but you can't do so here.
Grammatically, it means "That also is life."
もまた - - also
It probably refers to another line/section in the song mentioning something else that would elicit the 'that is life' response.
This is a good question to look at as well.
