Think it like this:
In the search for a cure for head ache, some guy took aspirin and did a magic rite, and he was cured; another guy just took aspirin and he was cured. Both account can be reproduced, and so far have worked. Therefore when doing analysis you can ignore the bit about magic, while it may be relevant in some mystical sense (the spirits are more happy if you do it, whatever), it is unnecessary to explain the cure from head ache.