Where fear is, happiness is not.Lucius Annaeus Seneca , one of my most devoted philosophers, the father of the Moralism, a great quote that represent the divergence of the duality, this quote do not accepts the terms of the Budism and thoughts and ideas like the "yin-yang" meaning. The thing is that we find everywhere this elements. Parmenides divided this terms too White-Black, Tall-short, the life is full of contradictions.
What we have here? fear is the passion that makes you unhappy, Happiness is the passion that makes you feel Fearless, the things that made us Fear are the things that are useless to the self development, if one controls our lifes there is no room to the other.
We can combine this two contradictions and live, but we can't use them at the same time, we always will act by fear or happiness, passions and feelings are two diferent things and we only can choose what of them use.