”The mind of man rests on a delicate balance between reality, the world of light, and the other darker world below the threshold of consciousness… and it is from this world of darkness which comes the evil destructive forces in man’s nature.”

It sounds like it might be the original Twilight Zone series. It was in black and white and the narrative sounds familiar.

My best answer would be its from the early 50’s/60’s possible in any of these 3 films.

~“Tales of the Darkside”

~“Twilight Zone”

~“The Tingler”

Also, the line appears in a song in the video game DeathSmiles.

It also appears in the song Reach Out by a Norwegian power metal band called Conception, on their 1997 album Flow.