byzantium, presence, and the internet
acheiropoieta; icons created by divine agency were known as acheiropoieta ("not made by (human) hands"). this category of miraculously created image was accorded special veneration throughout the history of byzantium. a significant number of acheiropoieta originated in the early byzantine period, before the advent of iconoclasm in the early eighth century. the most famous acheiropoieta included the mandylion, a white cloth imprinted with the face of christ, and the keramion, a ceramic tile which received the impression of christ's face from the mandylion. the ability to miraculously replicate was a common feature of acheiropoieta. a self-replicating machine is a construct that is capable of reproducing itself autonomously using raw materials found in the environment, thus exhibiting self-replication in a way analogous to that found in nature. a quine is a non-empty computer program which takes no input and produces a copy of its own source code as its only output. the standard terms for these programs in the computability theory and computer science literature are "self-replicating programs", "self-reproducing programs", and "self-copying programs". the quine concept can be extended to multiple levels or recursion, originating what has been called "ouroboros programs".