The call to soul-searching, that admonitory call that appears so often in literature, was also for many generations an essential part of Jewish practice.
For generations, both the maggidim in the cities and the itinerant preachers who visited the outlying hamlets and villages preached repentance and soul-searching.
Several days of the year were set aside for this purpose, such as the entire period from the beginning of the month of Elul (August/September) until the Day of Atonement itself.
What's more, it was for centuries the accepted custom among all the communities of Israel to set aside the eve of every new month as a day of repentance and fasting known as a "minor Day of Atonement."
On these days, the central theme of sermons and study was the soul-searching incumbent on the individual vis-a-vis the Creator and the reckoning that same individual must make with himself. Many people dedicated several hours daily to studying musar literature, which dealt with ways of improving and correcting the soul.
This kind of introspection was intended not for outstanding scholars and the pious but for the ordinary Jew—the Jew who throughout the year was absorbed with the problems of livelihood and business and all the other cares of daily life.
–Rabbi Adin Steinsaltz
From “Soul-Searching,” in The Strife of the Spirit,” by Rabbi Adin Steinsaltz