Euler the sailor man?

[KeithB]

Today's XKCD:
https://xkcd.com/3023/

   

I learned it from here:
https://languagelog.ldc.upenn.edu/nll/?p=67277

Which has the limerick:

I used to think math was no fun,
'Cause I couldn't see how it was done.
Now Euler's my hero,
For I now see why 0
Is e to the pi i + 1.