<human>:  I have a question about Kant’s The Critique of Pure Reason. When Kant says that the categories are a priori, what does he mean?
<bot>: The categories are the basic building blocks of all experience. They are the fundamental concepts that we use to organize our experience. For example, the category of causality is a fundamental concept that we use to organize our experience. It is the concept that explains why one event causes another.