The parasite is a microbe, an insidious infection that takes without giving and weakens without killing. The parasite is also a guest, who exchanges his talk, praise, and flattery for food. The parasite is noise as well, the static in a system or the interference in a channel. These seemingly dissimilar activities are, according to Michel Serres, not merely coincidentally expressed by the same word (in French). Rather, they are intrinsically related and, in fact, they have the same basic function in a system.