Monday's Riddle! Opposites Attract

Hello Riddlers! Here's this week's puzzle. Can you guess the theme? It's two sides of the same coin, flipped ; ) ~ F

One and the other- what could they be? Without them, there would be nothing to see. Something right fights with what's wrong, pulling the strings forever along. A label of tides is a mark to be told, piecing together those stories of old. Timelessly spaced from an end to an end- seen black or white, as foe or friend. This theme shall continue as we pass through our space- flashing by pictures, showing our face. Sometimes lovely, but also bad- one makes you happy, and the other is mad. 

Oh, what is it that dwells inside of us all? What makes us reach heights, or sink, and then fall? A ying and a yang, a dark and a light- a purposeful blend mixes truthful insight. So tell me now, what do you think? Is it from the same fountain we drink? For, when we stir the scene and brew emotion, we set the stage forward, churning in motion. 

What are we?

I gave you a clue!