sentences:  The issue of the environmental contribution to replication is somewhat open, since there are different conceptions of raw material and its availability.Von Neumann's crucial insight is that the description of the machine, which is copied and passed to offspring separately via the universal copier, has a double use; being both an "active" component of the construction mechanism in reproduction, and being the target of a "passive" copying process.This part is played by the description (akin to Turing's tape of instructions) in Von Neumann's combination of universal constructor and universal copier.