As dry as the reading is, a picture forms and musical insights emerge. When he was a youth, Beethoven was an organist. In today's terms you would say that was his gig. He worked a lot as an organist to support his livelihood. That bears keeping in mind as his musical thinking develops.
At 17 he made a trip to Vienna and met and played for Mozart. His studies were soon interrupted by his mother's illness, but at some point he heard Mozart play.
Czerny later recounts Beethoven's impressions of Mozart at the piano: "he had a fine but choppy way of playing, no ligato." Czerny adds that Beethoven played this way at first, treating the pianoforte like an organ. (Thayer, p. 88)