Fantasias are created intuitively - that is why they are expressed, in large measure, in a free manner (ex tempore) and for that reason they...

Fantasias are created intuitively - that is why they are expressed, in large measure, in a free manner (ex tempore) and for that reason they are performed, or composed correspondingly to the ideas appearing on the spur of the moment, regardless of the limitations connected with a type of measure [and meter]. That is how Johann Gottfried Walther described the genre of instrumental fantasia (Musikalisches Lexicon, Leipzig 1732). The opinion was not an isolated one. Most music theorists of the 1st half of the 18th century considered fantasias to be a kind of improvised music, or quasi-improvised one, characterized by almost complete freedom both in terms of their formal structure and musical expression. This point of view was also shared by Telemann’s friend, Johann Mattheson, who stated in his opus magnum (Der vollkommene Capellmeister, Hamburg 1739) that (…) pieces of that kind sound best if they are improvised, though they can be written down on paper. [As far as formal structure is concerned] they have so few limitations and so little order that it is hard to define them otherwise than just products of invention [of a performer, or composer]. For that reason they are marked with, first and foremost, (general) fancifulness. On the other hand, however, in the works of numerous composers from the 17th century (not only, though) one can find examples of fantasias which have almost nothing in common with the idea of free improvisation (ex tempore), just to mention a contrapuntal texture of the 17th-century English Fancies written for viola da gamba ensembles in mind. In reality, the name ‘fantasia’ frequently covered various types of a formal structure and musical expression.