Frankincense and myrrh were extremely expensive items in the first century AD (and for many centuries afterwards,too) and the symbolism was purely that the three kings were forking out for extremely valuable gifts, thus allegorically underlining the putative importance of the birth. Parr-apapa Pum!

Donkey fodder, infant formula and disposable diapers would probably have been much more practical, of course. But you couldn't expect kings to think of things like that, could you?

- Pfranz