By Memory or By Heart?

The Zanders finish The Art of Possibility discussing the difference between an orchestra playing 'by memory' or 'by heart'.

Players need to 'play freely', avoiding robotic tendencies. Something similar happens when playing with fear of mistakes versus intent of making plays. 

Confidence crafts plays while doubt drafts mistakes. 

Often, you need a short memory to prevent errors from snowballing. 

You can only be as good as you believe you are. If a player lacks self-belief, it's hard for them to excel. That explains why practice is vital, because it allows players to "stack good days" to boost confidence. Execution lifts belief and belief lifts execution.