I, too, have never read (nor remember hearing of) A.J. Nock - but I'll chime in, too.
A focus on 'breeding' was used as a rationale for the class of nobility, or nobles. In brief, it assumed that the product of two superior people would be children who were also expected to be superior. Even after the nobles were stripped of much of their authority in Europe (or their heads, in France), it was a quality that had some level of popular regard. At the time he (apparently) wrote, this theory was fairly wide-spread - you can find many references to it, and writings where it's an underlying precept.
It was not, in itself, racist - a person of good breeding from Frank stock was not necessarily to be viewed as 'lesser than' a person of common breeding of Saxon stock, or vice versa. It did lean heavily on family background, however, and it was not egalitarian.
It has come to be that discussion of this theory as regards human is impolite, or even politically incorrect, though in livestock, bloodlines are often seen as very important and relevant. Someone writing about "good breeding" now would be seen as rude, at best - though the families who are descendents of 'good breeding' do tend to marry within what they see as that class.
This, in my opinion, does not invalidate anything that Nock may have to say. An awareness of this may make it easier for you to understand what he says, giving you a better understanding of the basic precepts he took for granted, even if you disagree with those precepts.
Even a rabid, irrational racist may have good things to say - though they should be viewed through a lens that acknowledges that precept. Recent books have pointed toward the social flaws in A. Einstein, but nobody has said that we should ignore his mathematics because he was a lousy parent, or ignore his failures as a parent because of his expertise in math.
To decline to listen to what they have to say, even if you may disagree with it, serves nobody. To understand their precepts makes understanding what they say easier.
Heck - I've even read one of Al Gore's books. To condemn them without listening to what they have to say seems arbitrary, doesn't it?
Danno
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