R' Yaakov ben R' Aharon was born in 5548 (1787/8). He and his
brother, R' Yitzchak (author of the Talmud commentary Keren Orah)
were among the leading students of R' Chaim of Volozhin. It is
said that R' Chaim sometimes asked R' Yaakov to lecture in the
R' Yaakov was rabbi of Karlin and was recognized as one of the
leading sages of his generation. He is best known today for his
work Mishkenot Yaakov.
R' Yaakov is credited with "discovering" R' Yitzchak Elchonon
Spektor, who would be the leading posek/halachic authority of the
second half of the 19th century. This happened after R' Yitzchak
Elchanan lost all of his wedding presents in a business venture
and came to seek R' Yaakov's advice. Finding R' Yaakov immersed
in a Talmudic problem, R' Yitzchak Elchanan volunteered that the
question was answered in a certain work. So impressed was R'
Yaakov with the young scholar that he recommended R' Yitzchak
Elchanan for his first rabbinical position. (He also gave the
young scholar 40 rubles.)
R' Yaakov died in 5605 (1844/5). In his last minutes, he asked
his son to read to him from Ramban's Torah commentary because he
was very fond of that work. The tombstone which R' Yaakov shares
with his brother reads in part:
On the death of the two sons of Aharon - The staff of Aharon
gave forth a blossom and a flower and it was to the
congregation of Israel a miracle and a wonder. The honor of
Hashem shone on the house of Aharon. These two sons of his
were a wonder; they were known as the genius of Yaakov and
Yitzchak, and they raised a banner and a mast on the sea of
Torah. They were known to their nation for their [written]
works Kehillot and Mishkenot Yaakov and Keren Orah. Woe!
The cedars of G-d in the land; they studied the Torah of
Hashem the entire day. Who will teach our nation? Who will
close the breach?