With music, human may simulate the whole mystery of nature: its order, its beauty but also the unlimited complexity of its expression. Indeed, when listening to music, our perception being continuously beset by a huge flow of ordered stimuli, we feel as if we experience an idol-like representation of nature itself. One important aim of music analysis would be to explicit in detail the organization in music that induces so much effect in our consciousness. We propose to focus on this perceptive point of view of music analysis - or natural, again, because it considers the way music is really perceived. Because this task is so complex, computer is here of great interest. For this reason, and also because it may be preferable to analyze music objectively, the inner mechanisms that enable us to understand music have to be modellized. Here also, we will show the importance of a natural point of view, that is, a description of cognitive processes. We will discover, by the way, the essential cognitive mechanism of inference of analogy. Through this investigation, we propose a new analytical tool that would be able to analyze any kinds of music, including electro-acoustic and improvised - "real-time" - ones.