Rav Nosson Finkel, the Alter of Slabodka

The Chofetz Chaim was amazed by the way R’ Nosson Zvi transformed people.  “This craft can be practiced by R’ Nosson Zvi along.  We accept talmidim who are faithful and raise them to Torah and fear of G-d; but R’ Nosson Zvi accepts unworthy talmidim and turns them into G-d fearing scholars.  I create books; R’ Nosson Zvi creates people.”

From Sparks of Mussar by R Chaim Ephraim Zaitchik