Baruch Duvdevani served as the Executive Director of the Jewish Agency's Aliyah department. He recounted this frightful story:
It was the winter of 5716 (1956), immediately following the Sinai Campaign. Poland and the USSR had just signed a treaty allowing all Polish citizens who had fled to Russia during World War II to return to Poland. Jewish or not, they had the right to return, as long as they were Polish citizens on September 1, 1939, the day the War broke out. As a result of this treaty, thousands of Jews throughout Russia returned to Poland, and the majority of them subsequently immigrated to Israel.
I was privileged to spend that year, and the next, in Poland, helping organize this mass aliyah to Israel.
One December morning, when the temperature in Warsaw reached 19 degrees below zero (Celsius), I arrived at the Israeli embassy where we were stationed for our immigration work. The courtyard was filled with scores of people who had come from Russia to immigrate to Eretz Yisrael. I stopped and talked to each and every one of them at length. Our hearts were so filled with joy that we did not feel the cold.
I noticed an old Jew standing in the corner of the courtyard. He was bone-thin, with practically no flesh on his body. His dim eyes lacked any spark of life; his cheekbones protruded profusely; and his clothes were tattered and torn, despite the bitter cold. I realized immediately that the man wanted to speak with me and that he was simply waiting for me to finish talking to the others.
When I finished, the man approached me and asked if I was from Jerusalem. I told him that I was, and then he asked me if I knew Rav Kook, of blessed memory. I answered that I had been privileged to benefit from his exalted Torah and inspiring discourses. At that moment, the man burst into tears and said, "What a shame! What a shame that I did not listen to him."
He continued to sob for a while, and when he finally calmed down a bit, he told me his story:
In the early 1920's, I was a big manufacturer in one of Poland's famous industrial cities. One day, I decided to take a trip to Eretz Yisrael and spend Passover there. Being a religious Jew, I visited Rav Kook zt"l immediately upon my arrival. He welcomed me warmly and encouraged me to seek out the good of the Land and consider settling there. After a few weeks of touring, I returned to the Rav and asked him, among other things, what I should do regarding the second day of Yom Tov, seeing that I was a tourist.
The Rav answered with a smile: 'Decide right now to bring your family here and to build a factory in the Land. Then, you can keep one day of Yom Tov already this Passover, like all inhabitants of Eretz Yisrael.'
I took his answer jovially, and since the holiday was still a few weeks away, I decided to return at a later date and pose the question again, when it was more practical.
A few days before Passover, I went to Rav Kook and asked him the question once more. This time, the Rav answered sternly: 'I already told you that you should move here; then you may keep one day of Yom Tov starting now, even if you must return to Poland after Passover to settle your affairs.'
I said to him: 'Excuse me, dear rabbi, I have thought about it at great length; but in the end, da'ati lachazor — my intention is to return to the Diaspora. How, then, can I celebrate like the residents of Eretz Yisrael?'
The Rav banged his hand on the table and said with great emotion: 'Your da'at [intention] is to return? That is nothing but lack of da'at [sense]!'
The man continued in a broken voice: 'I did not listen to the Rav. I returned to the Diaspora and remained there. I lost my wife, my children, and my grandchildren in the Holocaust, and here I am today, lonely and desolate. I have come back here with nothing, after wandering for years through Russia. And I constantly recall Rav Kook's prophetic words: "That is nothing but lack of da'at!"
(From 'An Angel Among Men' by R. Simcha Raz, translated by R. Moshe Lichtman, pp. 257-259.)