Richard_Kennaway comments on Does the “ancient wisdom” argument have any validity? If a particular teaching or tradition is old, to what extent does this make it more trustworthy?

[Richard_Kennaway]

some of which still strikes me as completely unbelievable (like leaving water in the sun to absorb energy)

Ultraviolet disinfection?

Just a speculation, generated by nailing the custom to the wall and seeing what hypothesis accretes around it.