To Mr. Ravon, it seems that all is said very clearly in this excerpt from the book:
"Although Buddhist texts consider happiness as a simple concept, they still use phrases to describe as great bliss of enlightenment. Nirvana can actually be compared to a happy state: a state devoid of confusion and ignorance, without happiness or misfortune is certainly a state of bliss. But it's even better to understand the cause of error and ignorance never existed. If the alarm clock at the end of a nightmare is relief, happiness would never have dreamed of. It is in this sense that happiness is not happiness. For the benefit of the disciples seriously determined to break free of samsara, Siddharta stressed the futility of the search for happiness and peace in this life and in the hereafter. "Dzongsar Jamyang Khyentse