QUESTION: Who are the many that "run to and fro"? What knowledge is increased (Dan. 12:4)?
ANSWER: It is the last days of Israel's history under the times of the Gentiles. Another translation puts "run to and fro" as "shall diligently investigate." The Psalms, Prophets, Gospels and Revelation will be well investigated and guidance given to both converted Jews and Gentiles then where the gospel of the kingdom is preached. It is not yet. Daniel's book is still sealed.