John Stuart Mill wrote in a clear style on topics that we can easily relate to, and in a language composed almost entirely of words that we still use. However, the facility with which we believe ourselves to understand him is largely deceptive. This article presents five reasons why we can easily misunderstand him: (1) He often assumed knowledge about circumstances that were well-known when he wrote, but are now largely unknown. (2) Although the central words in his texts are still used today, many of them have undergone considerable changes in meaning. (3) In his discussions on social reforms he often shifted between different time perspectives. These shifts are often unobtrusive enough to be missed by modern readers. (4) He applied several rhetorical devices, in particular practical eclecticism and tactical overreach. (5) He chose to be silent for tactical reasons in some issues concerning religion and sexual relations. – For all these reasons, it can be a difficult task to understand what Mill meant, but it is certainly not a task with no chance to progress. To the contrary, it is one of those tasks in which perfection is never possible but improvement always is.