Tocata is an open musical meeting, attended by musicians and non-musicians, where all the music is improvised on the spot, spontaneously and 'intuitively' (as the participants themselves say), without scripts, conductors or rehearsals. The improvisation takes the form of an experimental sound dialogue between autonomous participants, who need to make agreements at all times about how the Tocata should sound, which musical styles and which instruments come into play. Notions of what is 'right' or 'wrong' in this context are suspended and can only make sense in the ephemeral moment of the immediate musical relationship. This book, based on the experiences reported by the participants of the Tocatas in Florianópolis (SC), aims to describe and analyse in depth the form and process of this improvisation. Along the way, we are invited to question our values and conceptions about the role that collective music-making plays in our lives. Thus, as we investigate the social relevance of Tocata and the human interaction that takes place there, we address some key points about the philosophy of musical improvisation itself in its connection with essentially ethical issues.