I disagree, it is possible to be happy and intelligent. Although with intelligence comes the ability to question and to philosophise, it is also possible to be happy by locking on to feelings rather than just rational thoughts. It is a situation of head versus heart. Balance is important. While an intelligent person may try to rationalise and over analyse situations, it is still possible to take a step back and enjoy the moment by locking out the rationality and accepting the pleasure of a moment. There remain so many unexplained things in life. To accept the unknown and not try to find ressons constantly will allow the intelligent person to be happy.