The head of a group of monks in Tibet found a stray cat and made it his pet. During morning and evening prayers, said playful cat had a habit of disturbing the other monks. So the order had a fancy gilded cage made for the cat, so that he might not prove such a disturbance during prayers. After some years, the head monk passed away. The twice daily ritual of putting the cat in the cage continued as always. After more years, the cat also passed away. The order then went to the local village to find another cat that could be placed in the cage, marking the beginning of prayers. Centuries later, learned treatises were written by the order's scholarly disciples on the liturgical significance of caging a cat while worship is being performed.
A good book to read on this topic would be Jakob Nielsen's UsabilityEngineering. -- Robert K. Brown
Also on: OldRulesWithForgottenReasons
Could it be that the ritual, once established, has taken on a new and deeper meaning? Yes. Or no.