The existence of the storyteller is such a deep secret for the Machiguengas, a people who, as the Schneils tell the narrator, are very open about every other aspect of their culture, because of what the storyteller represents. It is he who is the link between the remaining Machiguengas who are roaming around and also the link between their present and their past. The storyteller's role is to recite the myths and legends that define the Machiguengas and give them their identity as a separate culture. The narrator himself realises what their reluctance to talk about the storyteller signifies when he visits a settlement of Machiguengas that the Schneils have created. Note what he says:
It means that even in the most Westernised Machiguengas, such as the schoolmistress and Martin, there's an inviolable inner loyalty to their own beliefs. There are certain taboos they're not prepared to give up. That's why they keep them so thoroughly hidden from outsiders.
The role of the storyteller is to be the memory of the culture, the very heart that allows the Machiguengas to keep on functioning as a disparate yet united people. It is no wonder therefore that they are keen to keep that heart secret from those who, it could be argued, seek to threaten their identity and their sense of self.