Mozart was considered a genius of sorts in the sense that he started composing music from a very early age.
It is probably the idea that the music he composed influenced the genius in him to be sustained later in life. Since he continued to compose music his entire life. Afterall all children are born genius they usually fail to sustain it into their adult lives.
Baroque music music has a soothing effect in that the consistant tempo of 60 beats a minute slows the heart to that pace. It seems that the beat of music influences the heartbeat. A slow heartbeat of about 60 beats per minute is a resting beat and as such is a relaxed state. The relaxed state is found to be more productive to learning and remembering.
Alex