although their ephemeral existence had been known for centuries , no one quite knew exactly what these most peculiar beings were ; the commonest belief was that they were spirits who had somehow fallen to the earth and that was why their appearance was so startling and their sojourn in the human world so very brief ; this was also the reason why so many feeres worshipped them , considering their inexplicable , unpredictable manifestations a sign of their spiritness , and why the cave where they always materialized had over time become a sacred place , visited by hundreds of people even though most of the time it was empty , and suggestive of the seers passing only by the desiccated flowers , rancid food , long-extinguished molten candles and numerous votive objects and valuables left there by previous believers - offerings which ( or so the stories went ) remained entirely untouched by the seers , as though they were afraid of sullying their heavenly essence with the taint of all things human .