A Movie that starts with these two quotes:
 

Back when I was a teenager, I saw a movie that started with these two quotes by Nietzsche: "whoever fights monsters should see to it that in the process he does not become a monster” and “if you gaze long enough into an abyss, the abyss will gaze back into you”.

If my memory serves correctly, it was a strange movie about an old detective (50-60 of age) who specialize in catching criminals with sexual perversions or something of the sorts. Some details I remember is the use of a highlighter on the newspaper to "search" for these kind of people and that there was a crazy woman that was like the secret villain or something. In some scene, she was wearing a silver or a green aquamarine nightgown made of silk (i think). That's all I can remember.

Criminal Law (1988)?


This is from the Trivia section on IMDB for Criminal Law:

The film's opening prologue cites a famous quotation from the German philosopher Friedrich Nietzsche. The quote reads: "Whoever fights monsters should see to it that in the process he does not become a monster. And when you look long into an abyss, the abyss also looks into you."

From IMDB, the series Criminal Minds, Season 5, Episode 9 also starts with narration of that quote. I just confirmed as the show is on Netflix. The quote comes after the show's title intro.

No, unfortunately it is not. Criminal Law is about a lawyer. This movie was about a detective with white hair. Kind of the Clint Eastwood/Tomy Lee Jones type who doesn't take #$%# for an answer and seen enough of darkness to be tired of it.

It wasn't a series, it was a whole movie. It doesn't surprise me, though, that the quote appears in a lot of movies and series. It is highly over-used in my opinion and popular. That doesn't make it a bad quote, obviously. But I've seen it around enough and it is a damn reminder of this forgotten movie. PS: Hate to forget.

About what decade do you think it was released?

Mmm, that's a very good question. Maybe... 14-12 years ago? But it can be tricky because, maybe, it was an older movie seen around 14-12 years ago. But, if I recall correctly, the video quality was accurate with movies from 14-12 years ago.