<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 uses the term “a priori” to mean that the categories are innate to our minds, and are not learned from experience. For example, we know that objects have properties, like shape, size, and color. These are all a priori categories that we use to organize our experience.