Given the mysteries and fascinations of algorithms and computation, it is easy to forget a simple and basic truth: all computations take place in storage systems. Every representation is inscribed in a medium, from which it can be recalled later. The response of the medium affects computation time as much as the logic of an algorithm.
The wide use of inscription to record human knowledge is relatively recent in human history. The practice became widespread after the printing press around 1450. Before then, oral traditions dominated the way our ancestors kept and transmitted their knowledge. Today, everything is in writing, from ads to contracts, screen storyboards to film, musical scores to symphonies, blueprints to building inspector reports. With the computing age we have moved extensively to recordings in digital magnetic and optical media. The size of storage systems has grown from single computers with databases to the entire Internet.
Because of the richness of the kinds of objects we store, retrieve, and share, and the types of media and systems that hold them, recollection rests on a rich trove of principles that deeply affect our ability to compute and our perceptions of what computing accomplishes.