Knowledge means: "Why shall I serve the unreal illusion? Let me serve the reality. If my business is to serve and never to be master, always to serve, then why I shall serve the illusion? Let me serve the reality." That sense is called knowledge: Revision history
Diff selection: Mark the radio buttons of the revisions to compare and hit enter or the button at the bottom.
Legend: (cur) = difference with latest revision, (prev) = difference with preceding revision, m = minor edit.