If the twentieth century has lessons to teach us......

.............................one must surely be to beware of the self-appointed who throw out the collective wisdom of the past:

     With the decline of clerical power in the eighteenth century, a new kind of mentor emerged to fill the vacuum and capture the ear of society.  The secular intellectual might be deist, sceptic, or atheist.   But he was just as ready as any pontiff or presbyter to tell mankind how to conduct its affairs.  He proclaimed, from the start, a special devotion to the interests of humanity and an evangelical duty to advance them by his teaching.  He brought to this self-appointed task a far more radical approach than his clerical predecessors.  He felt himself  bound by no corpus of revealed religion.  The collective wisdom of the past, the legacy of tradition, the prescriptive codes of ancestral experience existed to be selectively followed or wholly rejected entirely as his own good sense might decide.  For the first time in human history, and with growing confidence and audacity, men arose to assert that they could diagnose the ills of society and cure them with their own unaided intellects:  more, that they could devise formulae whereby not merely the structure of society but the fundamental habits of human beings could be transformed for the better.  Unlike their sacerdotal predecessors, they were not servants and interpreters of the gods but substitutes.  Their hero was Prometheus, who stole the celestial fire and brought it to earth.

-Paul Johnson,  Intellectuals:  From Marx And Tolstoy To Sartre And Chomsky