The Husserlian concept of horizon proves to be not so much as a fixed and well defined concept, but rather the problematic crossing point of a set of situations which cannot be entirely explained in terms of ideality, presence or identity. The horizon is the one which, rendering all these possible or manifest, forms their forgotten background, and keeps itself always co-present, like an inexhaustible resource for all these manifestations. Therefore, throughout analyzing these problematic situations , we try to shed (...) a light on the structure of horizon and on its relation to the “theme” for whom it functions as horizon. Also, incidentally, we take notice of the ever-present tension to which Husserlian phenomenology is subjected when it chooses to explore in depth this horizonality. (shrink)