He was an outstanding personality, combining Torah scholarship with success in worldly affairs, and putting both in the service of his people.

Yehoshua Zeitlin, or Zeitles, was born in Shklov in the year 5502 (1743). After Wilno, Shklov was one of the most important Torah centers in Russia in those days. Yehoshua's first teacher was his father, Rabbi Tzvi Hirsh Zeitles, who introduced his gifted son to the world of the Talmud. Yehoshua was an excellent student. He had a brilliant mind and he studied Torah with love and diligence. By the age of ten years, Yehoshua was already thoroughly proficient in several Talmudic tractates.

One day a distinguished visitor came to their house. He was the famous Rabbi Aryeh Leib, author of the renowned book Shaagas Aryeh ("Roar of a Lion"), who headed a great Yeshivah in Minsk. The guest struck up a conversation with the young boy and was amazed to discover how far advanced the young boy already was in the Talmud. The famed Rabbi and Rosh Yeshiva urged the boy's parents to entrust the lad in his care. The parents agreed to let Yehoshua go to Minsk and become a student in the Yeshiva of the Shaagas Aryeh. At the Yeshiva, Yehoshua studied in the company of young scholars who were much older than he, and he excelled in his studies. Some years later, when the Shaagas Aryeh had to leave Minsk, Yehoshua returned home. He married the daughter of one of the most prominent Jews of Shklov, and became a merchant. He was highly successful in business and rose to become one of the wealthiest Jewish merchants in Lithuania and White Russia. Despite his extensive business affairs, he had set study-periods every day, morning and night, when he devoted himself to his beloved Talmudic studies. He also generously supported Torah institutions and scholars, and thanks to him Shklov became even more famous than before.

At that time Russia was ruled by Empress Catherine II. She appointed one of ber favorite generals, Zuritz, as governor of Shklov. He was an anti-Semitic and unscrupulous man, and he used his power to extort money and gifts from the Jews. This was the only way the Jews could avert all sorts of restrictions and oppressions, Yehoshua Zeitlin was the go-between and one of the major contributors to appease the greedy governor.

It is related that one day, as Yehoshua Zeitlin was sitting at his desk in his study, busy writing commentaries on the Talmud (he published a commentary on the well-known Halachic work Sefer Mitzvoth Kattan (SeMaK) and Responsa), he was informed that messengers had arrived from the governor to fetch him urgently. There was no time for him even to wash off the ink stains on his hands. As he shook hands with the governor, the latter noted the ink stains and took offense at the Jew's "impudence" in extending to him a "dirty" hand. Yehoshua Zeitlin, with an obvious reference to the governor's money-grabbing, showed him his open palm and pointedly retorted, "The ink stains are only superficial; my hands are clean!"

Zuritz's ever-growing pressure for bribery made life unbearable for the Jews of Shklov. Finally, they lodged a complaint against the governor with Queen Catherine. The empress then sent her favorite general, Count Potemkin, to investigate the complaint. Yehoshua Zeitlin headed a Jewish delegation to present their case before the Imperial investigator. At one point Zeitlin became so emotional when he described the plight of his fellow Jews that he cried excitedly, tears choking his words. Potemkin suggested he calm himself and stop weeping, to which Zeitlin replied, "It is not I who is crying and weeping—these are the tears and pleas of countless Jewish families whom Zuritz has ruined!"

He then gave Potemkin a detailed account of the Jewish position, and suggested practical ways and means which would not only ease their plight, but also bring considerable benefits to the development of industry and commerce in the land, and at the same time increase the government's revenue.

Potemkin was deeply impressed by the wisdom and obvious capabilities of this remarkable Jew, and decided to make use of his talents. The opportunity came when war broke out between Russia and Turkey (1787-92). As Commander-in-Chief of the Russian armies, Count Potemkin entrusted Yehoshua Zeitlin with the task of supplying the Russian army with food and clothing. Zeitlin carried out this responsible task so efficiently and honestly, that Potemkin praised him before the Empress. She invited him to the palace and bestowed on him the title of "Count Councilor" in recognition of his services.

Yehoshua Zeitlin was the owner of a large estate in the province of Mohilev. Here he built a Beis-Medrash and provided hospitality and full support to many Talmudic scholars and authors, to be able to devote themselves to their scholarly work without worry or distraction. His almost palatial home was always open to visitors, among them high ranking government officials and prominent merchants. It is related that one day a distinguished visitor came to his house. He was none other than Count Potemkin himself. They began a lively conversation standing, apparently each waiting for the other to sit down first. After a while Potemkin remarked, "We have been standing quite for some time. Do we have permission of the master of the house to sit down?" To which Zeitlin replied smilingly, "The commander-in-chief of the Russian armies is surely lord and master wherever he is; he is the commander here, too."

After Potemkin's death (1791), Yehoshua Zeitlin retired to his estate and devoted all his time to his Talmudic studies and writings.

At that time, the Chasidic movement began to expand rapidly under the leadership of the Alter Rebbe, Rabbi Schneur Zalman, a disciple of the great Maggid of Miezritch, the successor to Rabbi Israel Baal Shern Tov, founder of the movement. The Chasidic movement was still comparatively new, and almost completely unknown outside of the Chasidic circles. Suspicious of any movement that might introduce reforms or changes in the traditional way of the Torah and Halachah, many Rabbis opposed the Chisidic movement, fearing it might be a threat to orthodox Judaism. This sounds ridiculous now, when everybody knows that the Chasidim are the most orthodox and devout Jews, but in those days, about two hundred years ago, many well-meaning Rabbis not only rejected the movement, but also tried to suppress it. Among the opponents of the movement was Rabbi Aryeh Leib, the Shaagas Aryeh, and his disciple, Yehoshua Zeitlin. Some militant opponents, seeing the movement was steadily growing, resorted to a most shameful way of fighting the movement by denouncing its leader, the Alter Rebbe, before the Russian authorities as the leader of a movement which is dangerous not only to the Jewish people, but also to the Russian government and people. This led to the arrest of the Alter Rebbe, and for a time both his life and the future of the Chasidic movement were in serious danger. Eventually, the Alter Rebbe was able to prove his innocence and he was acquitted and released, which gave rise to the Chasidic festival of Yud Tes (19th) Kislev, the day of the Rebbe's liberation.

The Alter Rebbe made every effort to bring about a reconciliation between his opponents and followers. He was willing to meet face to face with prominent Rabbis of the opposition in order to discuss their differences, and explain to them what Chasidus really was. He was certain that he could convince them that the way of Chasidus could not possibly alienate Jews from Yiddishkeit; on the contrary, its purpose was to give Jews a deeper feeling of love and reverence for G‑d, love for the Torah and love for fellow-Jew, so that they would learn the Torah and observe the Mitzvos with greater dedication and joy.

Among three of the leading Geonim of the opposition whom the Alter Rebbe visited for the said purpose was Yehoshua Zeitlin of Shklov.

Years later, the famous Rebbe, Rabbi Menachem Mendel of Lubavitch, known as the Tzemach Tzedek (after his monumental work on Halachah), a grandson of the After Rebbe, related some episodes about his grandfather's encounter with Yehoshua Zeitlin. One of them had to do with the latter's attempt to test the Chasidic leader:

It happened that one of Zeitlin's servants was a gentile, who spoke Yiddish like a born Jew and also looked like a Jew. 'When the Alter Rebbe came to visit Zeitlin in his stately house, the host ordered the servant to bring some wine from the wine-cellar. He poured out a glass of wine for the guest and one for himself and waited for the Rebbe to recite the blessing over it. The Rebbe took the glass and began to recite the blessing with great kavono, but to Zeitlin's surprise concluded it with the words ". . . by whose word everything was created" (shehakol, instead of ". . . Creator of the fruit of the vine," which is the text of the blessing over wine). After tasting some of the beverage, the Rebbe told his host that the servant had brought up mead (a liquor of fermented honey, malt, yeast, spices and water) instead of wine. This is why he had made the blessing of shehakol. He added that since the non-Jewish servant had access to the wine, it places the whole wine supply in the cellar under the question of yayin-nesech (non-Jewish wine, or Jewish wine to which a non-Jew had access, which is not kosher).

Zeitlin, deeply impresed with the Rebbe's saintliness, observed, "It is in reference to you, and persons like you, that it is written, 'No evil shall happen to the tzaddik' (Prov. 12:21).

The Rebbe then delivered a profound Talmudic discussion on the prohibition of tripping up or misleading a person: "You shall not set a stumbling block before a blind man" (Lev. 19:14).

Zeitlin was now deeply impressed also with the Rebbe's Talmudic knowledge, and he wanted to know if his followers, the Chasidim, are Talmudic scholars and learn Torah regularly every day. "Do they have fixed study-periods for Torah?" he asked. The Rebbe answered in the affirmative, and Zeitlin said, "There is nothing new about that; our (non-Chasidic) laymen also have fixed study periods for Torah every day. What is it that makes your study periods specifically 'Chasidic'? What has the Chasidic way accomplished?"

"What the Chasidic way has accomplished is already quite obvious to one who really wants to know. As for the Chasidic way of learning Torah, it expresses itself in the fact that the study of the Torah is not merely an appointment in time, but it is at the same time also an appointment in soul." And the Rebbe explained that it is not enough for a Jew to have a set period of Torah study every day, thus consecrating that time to the study of the Torah but the learning must be in a way that the Torah should make an impact on his soul so that the entire daily life (even when not learning) is filled with the holiness of the Torah and Mitzvos.

After that meeting Yehoshua Zeitlin began to associate himself more closely with Chasidim. In due course, the prominent Zeitlin family became ardent Chabad Chasidim, followers of the Lubavitcher Rebbes.

Yehoshua Zeitlin wrote a Commentarv on the Sefer Mitzvos Koton (SeMaK), which was published together with the SeMaK in Kopust, 1820.

Yehoshua Zeitlin died Rosh Chodesh Elul, 5592 (1822).