Why did Immanuel Kant say that all knowledge begins with experience but does not all arise from experience?

Immanuel Kant’s assertion that "all knowledge begins with experience but does not all arise from experience" reflects his attempt to bridge the gap between empiricism and rationalism.

Kant argued that while all knowledge originates when our senses are stimulated by objects (the empirical component), the mind itself provides the necessary structure to make that experience intelligible. He proposed that human knowledge is a mixture of what is given through sense experience and what is contributed by the mind.12

Specifically, Kant identified certain "a priori" elements—such as the forms of space and time and the categories of the understanding (e.g., causality)—that are not derived from experience but are instead imposed by the mind onto the "stuff" of experience. These mental contributions are the necessary conditions for having any experience at all. By arguing that objects must conform to the requirements of human sensibility and rationality, Kant sought to explain how we can possess synthetic a priori knowledge—truths that are both informative about the world and necessarily true, independent of specific empirical observations.3124