A report from Anas describes several signs of the approaching Hour:
أَنْ يُرْفَعَ الْعِلْمُ وَيَظْهَرَ الْجَهْلُ
Knowledge will be taken away and ignorance will become widespread.
The removal of knowledge is not merely the disappearance of written books. It also involves the loss of sound religious learning among people and the spread of ignorance in its place. The sign underscores the value of sound knowledge and guidance.