Barzakh (برزخ) is the Quranic term for an isthmus or interworld — a boundary that simultaneously separates and connects two domains of reality. The Quran describes a barzakh between the two seas (fresh and salt) that neither transgresses (55:19-20). Ibn Arabi in the Futuhat al-Makkiyya elevates barzakh into a central metaphysical principle: it is the ontological membrane between the world of pure spirits (alam al-arwah) and the world of dense bodies (alam al-ajsam), neither wholly one nor the other. William Chittick in The Sufi Path of Knowledge explains that for Ibn Arabi, the human imagination (khayal) is itself a barzakh — the faculty that gives form to the formless and spiritualizes the material, making perception of the unseen possible.