We must be mindful that this was an improvisational era and that the specific divisions which separated compositions from performance had not yet come to pass. All composers were also performers and all performers were composers. With publication being both rare and extremely expensive, many details of interpretive directions were not indicated in the manuscript, but instead were left to be extemporaneously created by the performer as a test of his imagination and skill. This brings the realization that the Baroque score was but an outline of the composer's intentions, not an authentic document which showed how the composer wanted his work performed nor how anyone performed it. The fact that ornamentation was left almost entirely to the performer's judgment led to the fallacious conclusion that was purely a matter of individual tastes.
Nothing is further from the truth.
The contrary is true. Although the performer was free to select from a large number of stylish material, it was very precisely confined to 17th century convention. Exactly the same practices apply to matters of rhythm and temp. Although Baroque manuscripts reveal practically no tempo indications or dynamic markings, the composer's intentions were entirely clear to performers. The Old Tradition made a distinction between two movements, fast and slow.