2 Chronicles 34:1

Josiah was eight years old when he began to reign, and he reigned in Jerusalem one and thirty years.

Josiah took the throne as a child of eight and continued to reign in Jerusalem for thirty-one years, and his reign became the setting for a decisive spiritual turning. When the book of the law was read before the nation, the people were moved to profound contrition for their sins and turned back to the Lord with a renewed devotion. That widespread humbling and reformation showed what the public reading of God's requirements could accomplish in a backslidden land.

The same kind of deep, national repentance was the response John the Baptist looked for from his own call to repentance. As Josiah's generation had been stirred to return to the Lord upon hearing the law, so John expected his hearers to be stirred to repent and prepare for the coming One.