His own observations led him to a definite experience of the quality of the colour blue, for which he coined the phrase 'feebleness of blue' ('Ohnmacht des Blau'). In some way this colour seemed to him to be related to black. In order to rouse his artist friends and to stimulate their reflexions, he liked to indulge in paradoxes, as when he asserted that blue was not a colour at all. He found, however, as time went on, that in this way he came no nearer his goal. Although the splendour of colour in the Italian sky and the Italian landscape made a powerful impression on Goethe, he found not enough opportunity for systematic study to allow him to arrive at more than a dim surmise of some law underlying the occurrence of colour in nature. Still, there was one thing he took home with him as a result of his labours. He had grown convinced that 'the first approach to colours as physical phenomena had to be sought from the side of their occurrence in nature, if one would gain an understanding of them in relation to art'. Back at home, he strove to recollect the theory of Newton as it was being taught in schools and universities - namely, that 'colours in their totality are contained in light'. Hitherto he had had no occasion to doubt the correctness of this theory. Like everyone else, he had heard it expounded in lectures as an incontestable result of empirical observation, though without this ever having been shown to him by way of experiment. He convinced himself by consulting a manual that his recollection was correct, but at the same time he found that the theory there set forth gave no help in answering his questions.5 So he decided to examine the phenomena for himself. For this purpose he borrowed a set of prisms from a friend living in near-by Jena, the physicist, Büttner. Since, however, he had at that time no opportunity of arranging a dark chamber on Newton's lines, where the necessary ray of light from a tiny hole in the window-covering was sent through a prism, he postponed the whole thing, until in the midst of all his many other interests and duties it was forgotten. In vain Büttner pressed many times for the return of the prisms; at last he sent a mutual acquaintance with the injunction not to return without them. Goethe then searched for the long-neglected apparatus and determined to take a rapid glance through one of the prisms before he gave them back. He recalled dimly his pleasure as a boy at the vision of the world given him through a bit of similarly shaped glass. 'I well remember that everything looked coloured, but in what manner I could no longer recollect. I was just then in a room completely white; remembering the Newtonian theory, I expected, as I put the prism to my eye, to find the whole white wall coloured in different hues and to see the light reflected thence into the eye, split into as many coloured lights.