One the best tools we have as Jazz musicians is our ears - the more finely tuned they are, the better our ability to understand the music happening around us. Before Jazz method books, 'Real books' and playalong records appeared, a Jazz musician had to learn a tune using his or her ears and musical intuition on the spot (frequently on stage, at a gig or a jam session). This would have been a very different way of learning a tune rather than reading it from a lead sheet. Reading has its own advantages of course, and is a skill that should also be practised, but Jazz is a kind of music that comes alive when it starts to move away from what's written on the page. This is why transcription is such an important part of the Jazz musician's training. Writing out or learning to play a tune, a solo or a succession of chords from a recording is one of the best ways of training your ears, immersing yourself in the music, and learning from the masters themselves.