I found a long book excerpt with the passage (pdf!). It's a long discussion on history, ending with the swipe at present-day politicians. He mentions Roman Emperors here already, but speaks more about seeing Napoleon's invasion of Russia as parallel to the campaign he participated in, then Polish history in the context of a policy proposal he had in the fifties, the Kaczynski brothers -- and Brzezinski (whom he characterises as extreme Russian hater and extreme German hater). Schmidt then cuts off a discussion on Brzezinski (see below) with this closing remark that "the present generation of Politicians is relatively little interested in history" (with disclaimers regarding old men who think younger ones are less able and countries other than Germany).

The most interesting politico-klatsch part is when both Schmidt and his co-author/discussion partner Fritz Stern (a US historian of German origin) diss Brzezinski, though in different ways. I translate Schmidt's part:

Schmidt: Ich weiß nicht, ob ich das erzählen soll, aber ich hätte ihn beinahe mal rausgeschmissen aus meinem Büro. Er war damals Sicherheitsberater von Jimmy Carter, und in dieser Eigenschaft besuchte er den deutschen Bundeskanzler. Er redete in einer Weise mit mir, dass mir beinahe der Kragen geplatzt ist: arrogant, überheblich und agressiv.		Schmidt: I don't know if I should tell this but once I had him almost kicked out of my office. He was then security advisor to Jimmy Carter, and in that capacity he visited [me as] the German Chancellor. He spoke in a way with me that I almost boiled over: arrogant, overbearing and aggressive.
Stern: Haben Sie mal jemandem rausgeschmissen?		Star: Have you ever kicked someone out?
Schmidt: Einen Erzbischof, der im Auftrag des Vatikans einen Papstbesuch in Deutschland vorbereiten sollte, den hätte ich beinahe rausgeschmissen. Er hatte einen polnischen Namen, ich glaube aber, dass er Amerikaner war, denn nach meiner Erinnerung sprach er ein amerikanisches Englisch. Er ging davon aus, der Besuch des Papstes in Deutschland muss ein Riesenerfolg werden, und das kostet euch ungefähr 25 Millionen D-Mark. Werde ich nie vergessen! Der Bundespräsident hat ihm dann wohl tatsächlich hinauskomplimentiert.		Schmidt: An archbishop, who was on mission from the Vatican to prepare a papal visit to Germany, him I had almost thrown out. he had a Polish name, but I think he was American, because I recall him speaking American English. He believed that the visit of the Pope in Germany must be a huge success, and that costs you about 25 million D-Mark. I shall never forget that! The [figurehead] Federal President then actually bowed him out I think.

I only paraphrase Fritz Stern:

• Stern recalls discussing the 1956 Revolution in Hungary in the sixties with Brzezinski, who then sketched a map and drew in where the US should have dropped nuclear bombs to stop the Soviet invasion...
  
• During the Vietnam war, Stern and Brzezinski argued about its merits. Stern told him that having a 17-year-old son probably colours his anti-war stance. To which Brzezinski responded, he has a 15-year-old son, and wants the whole issue finished now -- meaning, in Stern's interpretation, he wants the Cold War won before his son grows up to be a soldier...

_{*Lunatic*, n.
One whose delusions are out of fashion.}