I first encountered her near the beginning of that golden age which nobody noticed was happening at the time; I mean the long decade between the fall of the Wall and the fall of the Towers.
If you wish to be pedantically exact about it, those retrospectively blessed dozen years lasted from the chilly, fevered Central European night of November 9, 1989 to that bright morning on the Eastern Seaboard of America of September 11, 2001. One event symbolised the lifted threat of a worldwide nuclear holocaust, something which had been hanging over humanity for nearly forty years, and so ended an age of idiocy. The other ushered in a new one.

What It Means

This is a placeholder explanation generated by the low-overhead model. It interprets "I first encountered her near the beginning of that golden age which nobody noticed was happening at the time; I mean the long decade between the fall of the Wall and the fall of the Towers.
If you wish to be pedantically exact about it, those retrospectively blessed dozen years lasted from the chilly, fevered Central European night of November 9, 1989 to that bright morning on the Eastern Seaboard of America of September 11, 2001. One event symbolised the lifted threat of a worldwide nuclear holocaust, something which had been hanging over humanity for nearly forty years, and so ended an age of idiocy. The other ushered in a new one." in the context of "Prologue (p. 2)" to mean that wisdom is timeless.