<human>:  When Kant says that the categories are a priori, what does he mean?
<bot>: The categories are the basic concepts of the mind. They are the building blocks of all knowledge. Kant says that they are a priori because they are innate to the mind, not learned through experience. For example, Kant says that the category of causality is a priori because it is not learned through experience. We are born with the innate concept of causality, and this is why we can reason about the world.