Avraham Yeshaya Karelitz (7 November 1878 – 24 October 1953), also known as the Chazon Ish (Hebrew: החזון איש) after his magnum opus, was a Belarusian-born Orthodox rabbi who later became one of the leaders of Haredi Judaism in Israel, where he spent his final 20 years, from 1933 to 1953.

Yitzchak succeeded their father as the rabbi of Kosava; he and his wife and daughter were shot to death in their home by the Germans in mid-1942.

Encouraged by Grodzinski and with Abraham Isaac Kook’s help, Karelitz settled in Eretz Israel, then the British Mandate of Palestine, in 1933.

[5] [6][7] Karelitz devoted his life to the study of Torah while simultaneously gaining knowledge in secular sciences such as astronomy, anatomy, mathematics, and botany.

After his marriage, he continued to lead an extremely modest life, his wife providing for their needs while he spent day and night studying Torah in-depth.

Like his brother-in-law Kanievsky, Karelitz "held no official position but nevertheless became a recognized worldwide authority on many matters relating to Jewish law and life.

There exists a common concern that any etrog may have come from a tree grafted with lemon branches, a practice which would result in nicer looking produce, though rendering the fruit unfit for the festival service.

After one Sukkot, Karelitz handed Michel Yehuda Lefkowitz a packet of seeds taken from the etrog he had used for the festival and instructed him to plant them in his yard.

Lefkowitz also allowed etrog growers to take cuttings from the tree to grow entire orchards of etrogim certified as kosher by Karelitz.

Although essentially an academic scholar, he applied himself to practical problems, devoting much effort to the strengthening of religious life and institutions.

In contrast to other great achronim such as Chaim Soloveitchik, Karelitz is known for avoiding formulaic or methodical analysis of Talmudic passages, instead preferring a more varied and intuitive approach similar to that of the rishonim.

A number of multi-volume biographies have been published about Karelitz, including Pe'er Hador, and the more recent Maaseh Ish, both in Hebrew.