A robot must obey the orders given it by human beings except where such orders would conflict with the First Law. - Isaac Asimov

It is enough for a Psychohistorian, as such, to know his Biostatistics and his Neurochemical Electromathematics. Some know nothing else and are fit only to be statistical technicians. But a Speaker must be able to discuss the Plan without mathematics.

[B]y 1204, the only place where the entire body of Greek learning existed, still intact, was Constantinople. As a result of the crusaders' conquest, however, Constantinople was ruthlessly pillaged and destroyed and almost all the great treasures of ancient Greek learning were lost forever. It is because of that sack, for instance, that we have only seven plays left out of the better than one hundred written by Sophocles. The tragedy of 1204 can never be undone and for all of time, only bits and pieces of the marvelous Greek world can be known to us.

Here in the Periphery they've lost nuclear power. In Gamma Andromeda, a power plant has undergone meltdown because of poor repairs, and the Chancellor of the Empire complains that nuclear technicians are scarce. And the solution? To train new ones? Never! Instead they're to restrict nuclear power." And for the third time: "Don't you see? It's Galaxy-wide. It's a worship of the past. It's a deterioration — a stagnation!