More on psychopathy and its relationship with Narcissism

Here is a quote from Hervey Milton Cleckley, M.D. famous book - The Mask of Sanity, that describes the difficulty psychopathic people experience with deriving meaning from their lives the way a normal people do. While psychopathy is a deeper and more troubling condition than Narcissism (though lines are blurry when we are talking about extreme cases of NPD.) I can not help but see some parallels when it comes to socially appropriate behavior:

"He (the psychopath - NPDrecovery note) cannot achieve true and abiding loyalty to any principle or any person.

He is not adequately moved and he does not find subjective stimuli to make the major issues of life matter sufficiently to promote consistent striving."

In other words, the difficulty lies with not being able to connect and produce emotional satisfaction (or distress) from upholding (or violating) one's values, since values and by extension, rules that protect those values are not given serious consideration in the first place.

What most people find hard to understand is, in effect, a very simple concept: psychopaths and, to some extend, Narcissist behave in a certain way because there is no "barrier" to hold them from violating particular principles. In fact, they do not see it as violating at all, since there are no such values/principles in their world... 

For us breaking someone's heart, betraying trust or taking advantage of a person's kindness is unthinkable, but for them it is just a matter of opportunity to fulfill their needs.

Once again, I see a big difference between psychopathy and NPD, but they are, in effect, within one spectrum (if on the different areas) of a disturbed mind and so one can perceive similarities even when equating the two would be too much of an assumption...