Rav Yaakov Yitzchok Ruderman (March 7, 1901 - July 11, 1987) was the Rosh Yeshiva and founder of Yeshivas Ner Yisroel of Baltimore. Rav Ruderman founded the yeshiva in 1933, and served as its Rosh Yeshiva for 54 years, until his passing.
Threaded through every chapter of Rav Ruderman’s life are stories of his complete immersion in learning to the exclusion of all else. Once, a talmid was speaking with an elderly man, a native of Lithuania. Upon hearing the name of the Rosh Yeshiva, the man exclaimed, "Ruderman from Dolhinov? Can’t be! That’s extremely interesting. He was well known in the town, a ten year old boy who would walk down the main street talking to himself! He did this every day from morning until evening. And you say this boy became a Rosh Yeshiva?!"
Upon returning to Baltimore, the bochur reported this conversation to the Rosh Yeshiva, who confirmed it. "I would walk back and forth along the street, learning pages of Gemara by heart. In my pocket I kept a small Gemara and occasionally when I was afraid I hadn’t repeated what was written accurately enough, I would look into the Gemara and then continue."