Historical Blind-Spots
"The quality of the world we live in," Barfield cautions us to remember in History, Guilt, and Habit, is determined not only by what we perceive but also by what we fail to perceive" (HGH 71).

Historical blind-spots occlude our vision:

When we look back on past periods of history, we are often confronted with inconsistencies and blind spots in human thinking, which to us are so palpable that we are almost astonished out of belief. We find it hard to credit the inescapable fact that they remained, for decades or for centuries, completely invisible not only to the generality of men but also to the choicest and wisest spirits of the age. (SA 167)1

Our own worst blind-spot is easily identified:

I believe that the blind-spot which posterity will find most startling in the last hundred years or so of Western civilization is, that it had, on the one hand, a religion which differed from all others in its acceptance of time, and of a particular point in time, as a cardinal element in its faith: that it had, on the other hand, a picture in its mind of the history of the earth and man as an evolutionary process; and that it neither saw nor supposed any connection whatever between the two. (SA 167)

And, as Burgeon realizes in Unancestral Voice, we need not look far to understand the cause of this puzzling lacuna in our understanding:

It was hard indeed on the human mind that the moment at which it first began to entertain the idea of transformation should also be the moment at which it was itself in the act of becoming the transforming agent! No wonder if it had failed, as yet, to understand. No wonder if was still looking desperately round outside for that which it was itself just beginning consciously to be. (71)

See in particular "The Coming Trauma of Materialism" (RM 187-200); Worlds Apart, passim.
1Barfield offers the following examples: "the Athenian emphasis on liberty-with the system of slavery accepted as a matter of course; the notion that the truth could be ascertained and justice done with the help of trial by battle; the Calvinist doctrine of pre-election for eternal damnation; the co-existence of a Christian ethic with an economic doctrine of ruthless laissez-faire . . . " (SA 167).