This could be a cliche or simply a fragment of my imagination,but in the hillsides of rural Spain and Mehico,you'll find some very old and wizened flamenco guitarists who've probably never been to school but who are absolute virtuosos at what they do.
And there are sheet music classical guitarists who are again absolute virtuosos.
Lesson(assuming the above is true:)):
You can be absolutely teriffic whereas you can't tell the differencec between a crotchet and an illustration of a sperm.
And you could also become absolutely teriffic coz of being able to tell the differencee between a crotchet and an illustration of a sperm.