If you extemporize you can get much closer to your audience.
"The Art of Public Speaking"
Dale Carnagey (AKA Dale Carnegie) and J. Berg Esenwein
Could not a clever girl throw herself into the part of Alcestis, or chant the majestic verses of Cleanthes, or extemporize a hymn upon the spring, or hold an argument on the pulchrum and utile, without having any leaning towards Christianity?
"Callista"
John Henry Cardinal Newman
We are told by his biographers that he was accustomed to extemporize at school, and had such a knack in portraying the characteristics of his school-fellows in music as to make his purpose instantly recognizable.
"Great Violinists And Pianists"
George T. Ferris