One of the paradoxes of Parkinson’s disease is that it seems to build up in its sufferers both an extraordinary need to act, and a simultaneous blocking of action. Medications, like the L-DOPA made famous in Oliver Sacks’ 1969 account Awakenings , can get many such patients ‘unstuck’ (though it’s more harrowingly complex than just that). But sometimes the unblocking can be brought on by seemingly far subtler treatments: by music, by the visual cues of another person’s normal gestures
One patient, who was so eloquent on the subject of music, had a great difficulty in walking alone, but was always able to walk perfectly if someone walked with her. Her own comments on this are of very great interest: ‘When you walk with me,’ she said, ‘I feel in myself your own power of walking. I partake of the power and freedom you have. I share your walking powers, your perceptions, your feelings, your existence. Without even knowing it, you make me a great gift.’ This patient felt this experience as very similar to, if not identical with, her experiences with music: ‘I partake of other people, as I partake of music…’
from Awakenings, by Oliver Sacks, p.248 (1983 epilogue)