The 20th century is the most diverse classical music period.

The classical liberalism in the 17th and 18th century in Europe referred to the ability that made the classic liberal focus more on what they said and wished.

Classical liberalism in the 17th and 18th century in Europe did mark a distinction from tradition as people were given the ability to say and do whatever they wished.

No. Μonophonic and polyfonic styles of music -like gregorian hymns,organoum, discantous- were the first types of music(dating back to 7th-9th century). Soon the barok writers took over and eventually after the 17th-18th century classical music came up, followed by the romantic century and then the contemporary.

Classical music (as we know it today) has existed since the 9th century and into the present day. The term "classical music" wasn't applied formally until the 19th century.