How print spread the Ninety-Five Theses

In 1517 Martin Luther proposed the Ninety-Five Theses for a theological debate about indulgences, the remission of church-imposed penalties for sin. Printers quickly carried the text beyond university circles, and the controversy helped set the Reformation in motion. However, hundreds of thousands of copies of the theses themselves are not established: the Library of Congress describes three early editions from 1517 and estimates about 300 copies of each. These are estimates for particular editions, not a complete count of every copy.