Right and Wrong
Good and Evil
Order and Chaos
Success and Failure
Heaven and Hell

Or rather,

Light and Darkness

Can there be Light without Darkness?
They are two sides of a coin
One cannot exist without the other
As they both define each other
One cannot be ‘good’
Without knowing what is ‘bad’
One is meaningless without the other
No joy can truly be appreciated
Without first having a sense of sadness

Which one of them comes first?
There is neither first nor second
They are always together
But for most of the time...