The mind becomes accustomed to things by the habitual sight of them, and neither wonders nor inquires about the reasons for things it sees all the time.
The real enemy of happiness is the mind's fixations and delusions... If you have the right mind, you can overcome anything - you can be happy, no matter what.
As human beings we have the same experience of destructive and constructive emotions. We also have a human mind capable of developing wisdom. We all have the same Buddha nature.
A cup is useful only when it is empty; and a mind that is filled with beliefs, with dogmas, with assertions, with quotations is really an uncreative mind.