The word sthanu means "a dry tree without leaves." From a distance one may mistake such a tree for a person. This is called sthanu-purusa. Although Sri Caitanya Mahaprabhu was living in Vrndavana, the inhabitants considered Him an ordinary human being, and they mistook the fisherman to be Krsna. Every human being is prone to make such mistakes. Sri Caitanya Mahaprabhu was mistaken for an ordinary sannyasi, the fisherman was mistaken for Krsna, and the torchlight was mistaken for bright jewels on Kaliya's hoods.