Why is "-the Maxim-" in the title? I suspect there may be a Your Lie in April title spoiler situation here, or quite possibly I'm just dense. I'm on episode 10 of Parasyte -the Maxim- and I have been wondering the whole time what the title means.  At a guess, it could involve how episode 1 starts and ends.


start: Someone on Earth had a sudden thought.
end: Someone on Earth had a sudden thought. "Life must be protected."


(The end quote appears at time mark 20:40.) The Google dictionary defines maxim as "a short, pithy statement expressing a general truth or rule of conduct".  So is that the maxim, Life must be protected.? If so, there will probably be a further reveal late in the series. Or am I way off base?

If the actual answer is a spoiler, please put it in a spoiler block. I'll hold off reading that part until finishing the series.
I believe you are right on the mark that the maxim is "Life must be protected." 

From what I remember, the theme is pretty consistent throughout the entire series, but the overarching idea tied to the maxim is that all life is valuable, regardless of species. 

It's a bit philosophical for an anime about aliens that hijack human bodies and blend in so they can eat other humans while no one is looking, but bear with me.



One way that the series plays into this maxim is by seemingly asking "Who is really a monster?", as in "Who really deserves to live/die?"


  After the initial brutality of the Parasites, some of them start to realize that the best way to continue their existence is to co-exist with the humans. However, most humans oppose this idea completely, due to first impressions and not-so-peaceful Parasites. This idea comes to a climax in episode 21 where the presumed Parasite mayoral candidate Hirokawa condemns humans for not being able to live alongside Parasites and is shot to death. Only after this is it revealed that Hirokawa was fully human the entire time.


Another scene that depicts Parasites as not complete monsters is in Episode 18,


  when Reiko sacrifices herself to save her son. 




The other way that this maxim is used throughout the series is the idea of survival. 

That is, the Parasites simply seek to survive, and


  as mentioned above, seek to cooperate with humans, though they are rejected entirely and effectively forced into hiding, lest they be hunted, as seen in Episodes 19-20.