"One of the concepts essential to molecular manufacturing is that of a self-replicating manufacturing system. That concept has lagged behind in its acceptance"

Ralph Merkle's quote is describing the idea of a self-replicating production system, which is an essential part of molecular manufacturing. This principle has not been extensively accepted, and has dragged in its approval. This idea includes the use of nanotechnology to create machines that can duplicate themselves, and therefore produce more devices. This could transform the manufacturing industry, as it would allow for the production of products with greater performance and at a lower expense. Nevertheless, the idea has not been widely accepted due to the prospective risks connected with it, such as the capacity for the machines to become unmanageable and trigger damage. Despite this, the principle of self-replicating manufacturing systems is a crucial one, and its acceptance is important for the advancement of molecular manufacturing.