It is unfair to cite a man who is still alive, whom I do not know, even in passing, and who may take exception to being cited. Yet Yehuda Avner is perhaps the most qualified person on the planet to shed light on Prime Minister Netanyahu’s speech to Congress. Mr. Avner is a diplomat who spent a career writing speeches and then advising every Israeli prime minister from Levi Eshkol and Golda Meir to Menachem Begin, Shimon Peres, and Yitzhak Rabin.

His best-selling book, “The Prime Ministers,” was published in 2010 and establishes Mr. Avner’s humor and ear for a story. He attributes to Caspar Weinberger the following explanation for his failure to be elected attorney general of California: “The Jews knew I wasn’t Jewish and the gentiles thought I was.” But it is the stories from Mr. Avner’s own career, sitting discretely with U.S. presidents and Israeli prime ministers, that provide the insight into Mr. Netanyahu’s speech.

In the mid-1960s, Prime Minister Eshkol sent Mr. Avner to deliver a note to Harry Truman to thank him for recognizing Israel in 1948. Then in his 80s, the ex-president was still residing in the Victorian home at Independence, Missouri. Truman invites Mr. Avner for a stroll in the neighborhood and then unexpectedly asks his Israeli guest to join him inside for a bourbon (coffee for Mr. Avner). Turning to the topic of his friend and former haberdashery partner, Eddie Jacobson, Truman acknowledges that he agreed to meet with Chaim Weizmann only because it was the one favor Jacobson ever sought.

“I knew then what I had to do,” Truman said. “I had to handle those stripe-pants boys, the boys with the Harvard [he pronounced it ‘Ha-vud’] accents. Those State Department fellows were always trying to put it over on me about Palestine, telling me that I really didn’t understand what was going on there, and that I ought to leave it to the experts. Some were anti-Semitic, I’m sorry to say. Dealing with them was as rough as a cob. The last thing they wanted was instant American recognition of Jewish statehood.”

“I had my own second thoughts and doubts, too. But I’d made my commitment to Dr. Weizmann. And my attitude was that as long as I was president, I’d see to it that I was the one who made policy, not the second or third echelons at the State Department. So, on the day the Jewish State was declared, I gave those officials about thirty minutes notice what I intended to do, no more, so that they couldn’t throw a spanner into the works. And then, exactly eleven minutes after the proclamation of independence, I had my press secretary, Charlie Ross, issue the announcement that the United States recognized Israel de facto. And that was that.”

The story has been told many times, but never so well as Truman told it to Mr. Avner. After the sniping at Mr. Netanyahu as a “chickens**t” by officials of the Obama administration, can one even imagine the president standing up to the State Department to recognize Israel? Or even saying “rough as a cob,” “striped-pant boys” or “my commitment to Dr. Weizmann?” The mind reels at a world fallen from view.

Mr. Avner relates how the reelected prime minister, Menachem Begin, is due to meet in Washington with President Reagan. Relations had been strained by Israel’s bombing of the Osirik nuclear reactor and America’s sale of military equipment to Saudi Arabia. Nonetheless, here is President Reagan’s greeting to Begin on the White House lawn. It concluded with these words:

“I welcome this chance to further strengthen the unbreakable ties between the United States and Israel, and to assure you, Mr. Prime Minister, of our commitment to Israel’s security and well-being. Your strong leadership, great imagination, and skilled statesmanship have been indispensable in reaching the milestone of the past few years on the road toward a just and durable peace in the Middle East.”

“Reagan,” Mr. Avner relates, “then turned to address Begin directly, and the rich timbre of his voice almost cracked when he said, ‘I know your entire life has been dedicated to the security and the well-being of your people. It wasn’t always easy. From your earliest days you were acquainted with hunger and sorrow, but as you have written, you rarely wept. On one occasion you did – the night your beloved State of Israel was proclaimed. You cried that night, you said, because ‘truly, there are tears of salvation as well as tears of grief.’ Well, with the help of God, and us working together, perhaps one day for all the people of the Middle East there will be no more tears of grief, only tears of salvation. Shalom, shalom, to him that is far off and to him that is near.”

These are the words spoken between strategic allies. Shalom, shalom. Now they read as a reminder of all that has been lost in the current White House, with so much more yet to lose as the President runs feckless on the world stage, playing Obama Unbound. In 2011, Mr. Avner was asked how he imagined Begin would, were he still alive, “deal with Iran’s threats to Israel and its drive to build nuclear weapons?”

“Begin,” Mr. Avner replied, “had a doctrine which said — one: If an enemy of our people says he seeks to destroy us, believe him. And two: Israel will never allow an enemy of our people to manufacture weapons of mass destruction against us. Iran fits that bill totally, and Begin would act accordingly. Exactly how I cannot presume to know, but believing as he did in a God of Israel, and haunted as he was by the Holocaust, and driven by the vow that he would never allow such a catastrophe ever to happen again, I can imagine that his policies, overt and covert, would be aggressively focused to make it plain to the West that if it doesn’t act, Israel, in one shape or another, would.”

The interviewer, Michael Freund, was the former deputy director of communications to Prime Minister Netanyahu. Then again, why not take it directly from the Prime Minister Netanyahu’s own words to Congress. “The days when the Jewish people remain passive in the face of genocidal enemies, those days are over.” It has been reported that the line received the biggest cheer, in a speech interrupted by applause 40 times in 40 minutes.

Mr. Levin manages an investment banking firm in New York.