"Heard melodies are sweet, but those unheard Are sweeter; therefore, ye soft pipes, play on; Not to the sensual ear, but, more endear'd, Pipe to the spirit ditties of no tone" (Keats, Ode on a Grecian Urn) Imaginary describes what does not exist at all or only in the imagination, with no reality. Applied to landscape, the concept of imaginary landscape can however have two very different meanings: 1, the one radical, internal and dreamy, in the sense of a phenomenon existing only by courtesy of the imagination (an instance well defined by the German Einbildungskraft, the strength or power to carry or concentrate an internal image), without any intervention by the outside world; 2, the other, of equally strong interest, is concerned in the end simply with the landscape, knowing that - as a phenomenon - it only exists in someone's awareness. All landscape true to life will of course be imaginary or otherwise: for nature to become landscape, it must be imag-ined, transformed into image. These two possibilities, the fanciful or visionary self-fiction on the one hand and the manufacture of the image of the real on the other, are each exposed to the problem of translating what is only seen or only exists internally. The romantic poet Coleridge expressed in his famous Notebooks the whole difficulty of finding the language corresponding to what he perceived, momentarily and miraculously, in his imagination: "The Head of Glen Nevis how simple for a Painter/ & in how many words & how laboriously, in what dim similitudes & slow & dragging Circumlocutions must I give it - so give it that they who knew the place best would least recognize it in my description." (Note 1489) In speaking of painting, we have used the term imaginary or fantastic landscapes for a long time. Joachim Patinir, "der gut Landschaftsmaler", according to Dürer, shows in his Weltlandschaften (world landscapes) an exuberant and unlikely panorama in which the fantastic is present in very different forms. The wonderful extension of the enormous landscape scenes become in his hands the theatre of a pictorial ensemble as difficult to decipher as the spectacular visions of a Bosch or a François de Nomé. The 'imaginary' attribute is later applied also to Francesco Guardi and Gaston Redon and, in the 20th century, to Salvador Dali. Now, the fantastic, fictional and impossible character of these landscapes must not make us forget their totally constructed and composed aspect; the imaginary, a priori a symbol of total liberty of spirit, is written down the ages in a restraining and highly rhetorical syntax. Another tradition, more interesting still in terms of its epistemological and aesthetic implications, finds its focal point in the famous landscapes composed in "blots", invented by Alexander Cozens. The imagination functions for this English painter and theoretician as the essential pathway leading from the real to post-mimetic representation. It behoves the artist "with the swiftest hand to make all possible variety of strokes upon the paper, confining the disposition of the whole to the general subject in the mind". With Cozens, things were truly overturned: the imaginary landscape is the only true landscape, while those of the academic tradition appear as fiction.