How did Kant explain the free play of imagination and understanding?

In his Critique of Judgment, Immanuel Kant explains that the "free play" of imagination and understanding is the foundation of aesthetic experience, distinguishing it from ordinary perception.12

In ordinary thought, the imagination is bound by the concepts of the understanding; it synthesizes sensory intuition with a specific concept (such as identifying an object as a "book") to form a determinate experience. In contrast, during aesthetic experience, the imagination is "free from concepts". It engages in a harmonious, free play with the understanding, where the imagination grasps the object without being restricted to any definite concept.12

This state of harmony is not cognitive, as it does not rely on argument or conceptual analysis, but is instead felt as an immediate delight. Because this free play of cognitive faculties is common to all human beings, Kant argues that individuals can rightfully impute their aesthetic pleasure to others, representing their judgment as having universal validity despite its basis in subjective feeling.2