The ancient egyptians believed that illness was the result of attacks from demons.  When they got sick and sent for a doctor, the treatment the doctor provided was often more like an exorcism than the treatments we get from modern doctors.  The doctors did give them tonics made with herbs and other physical treatments, but mostly they prayed to remove the offending demon.  In the case of the common cold, he would shout this out:

Begone Cold, son of Cold!
You who break bones,
Who shatters the skull,
Who digs into the brain,
so that sickness overtakes the the seven openings of the head
which are the servants of Ra, and the praise-singers of Thoth,
See, I have brought the remedy against you!

And that was supposed to cause the demon to leave.  The idea is not so ridiculous.  We are exposed to cold virus and other harmful germs all the time, but we're not always sick.  The reason is because our immune system fights them off.  But the immune system gets weakened by physical things like chemicals in the food and water as well as non-physical things like negative thoughts and beliefs: negative energies which is just another way of saying demons.  So maybe we should try using prayers like the one listed above when we are sick and we just might get well sooner.  It's certainly smarter than constantly spraying ourselves and everything around us with anti-bacterial products that only succeed in creating nearly indestructible super-bugs.