On how the Cambridge spies became "traitors to their class":

"The obvious yet rarely understood stroke of secret service genius behind all such operations was the simple recognition of an essential bond between the so-called 'establishment' (by which is meant little more than the elite of a given society), and what Lionel Trilling called the 'adversary culture' – that part of society which, by virtue of its superior education and critical equipment, develops for itself a leveraged position within the middle class, based in ambiguity and the perspectives of criticism and argument, insight and protest. The adversary culture is a branch of the middle class; usually its most vigorous intellectual and artistic wing. It is drawn, albeit ambivalently, to radicalism; radicalism is part of its vision of freedom and truth. The radical solution, it imagines, would tear aside the bourgeois facade; radical insight, it suspects, reaches the deepest truth. In fact the ability really to grasp, if not embrace, radical insight is what the adversary culture believes sets it apart from the vast hypocritical and second-rate middle class to which it belongs but also wishes – understandably, properly – to distinguish itself."

from Double Lives by Stephen Koch