improv was mentioned some,just waned to contribute my little bit.
i think it helps to understand that the definition of improvisation in our modern common context/understanding can and is frequently different (and i'd say 'limited' ) than improvisation as practiced in the 17th and 18th centuries.
the fact that composers were trained extensively in, and encouraged to 'improvise' is well established and understood to be an important contributing part of how they were able to compose so many works in such a short amount of time (relatively, and for those that did published extensively).
there's visting lecturer coming to school next week to give a special topic discussion on this very topic. if anyone is interested i can give you the contact information via pm to the school contact for the lecture series, they might be able to put you in contat with the professor or even provide access to a recording or transcripts/notes, etc if those are available. i want to attend and would post my own notes but i have a class conflict.
also, this might be good reading on the matter for some.
pdf attached.
excerpt
"...The Baroque period thus saw a number of institutional and socioeconomic changes that impacted upon improvisation, and as such it will be my principal focus here.8 But what do we mean precisely when, as performer, musicologist or—as in the case of many of us historical performers, embodier of both roles—we invoke the phrase ‗Baroque improvisation‘? Do we mean, as Paul Berliner asks rhetorically, ‗picking notes out of thin air‘,9 perhaps in this case the spontaneous generation of an entirely new piece indistinguishable from a 17th or 18th-century composition? Do we mean the composition of new melodic parts above a provided ground bass, a new set of diminutions or a double for a 17th-century air de cour, or the addition of new material in a more limited fashion, such as a cadenza in a sonata or concerto? Or does Baroque improvisation imply only the addition of a few ornaments to a previously-composed score, based on an assimilation of the surviving written-out examples and treatises from the period? Is it acceptable to term such ornaments and cadenzas ‗improvisation‘ if they are written down, memorized or sketched out in advance, or must they literally be performed on the spot? Would we include in a discussion of Baroque improvisation the realization of a basso continuo part, even though the chords are usually indicated above the bass line, and good voice- leading rules and contemporary treatises place significant constraints on interpretation?10 Where exactly do we draw the line between spontaneity and pre-planning, and between interpretation, composition and improvisation? Improvisation, as Bruno Nettl suggests, would seem to occur on a continuum; its definition is socially determined and dependent on cultural context.11 This is true, I would argue, not only for non-western musics, jazz and other genres, but also for European music composed from 1600 to 1750—as practiced by 17th and 18th-century musicians, but also by 20th and 21st-century musicians in the early music revival....
Topic: Busoni vs Mozart vs Bach