Printing press

Around 1440 in Mainz, Johannes Gutenberg combined existing pieces: a screw press from wine and paper making, oil-based ink, and metal type that could be cast from a mold and reused. He did not invent printing. China and Korea already printed with blocks and with movable type. What Europe got was a system matched to an alphabetic script, so a small set of letters could print any page.

The contribution is copies. A book that took a scribe months could be printed in days, and the next book used the same type. Scientists and craftsmen could read the same text instead of a drifted handwritten copy. The steam engine, the laws of motion, and the battery all spread because this channel existed.

The first major book, the Gutenberg Bible, is from the 1450s. The social effect lags the machine. Literacy does not jump in a year. Over the next century, pamphlets and science do.

Without writing and paper, the press is a press. The contribution is not the screw. It is reusable letters on cheap sheets.