commiting a change from command line with newlines.

Hello,

I'm trying to write stanzas in my commit message, and naturally the ASCII newline character is the best tool for this, beautifully integrated throughout my whole system, from my keyboard to my screen.

My question is, how can I add a newline from the git command line without opening an external program like vi, atom, notepad, word etc...

Since I'm using a unix like system I even tried with pipes (and xargs, the necessary evil) but with something like "printf "a\nb" | xargs git commit -m" b gets interpreted as something else. 

Does anybody know of a way to adorn a commit message with newlines in a single git commit command? Thanks in advance.