An entry the Guide forgot to include

There is, somewhere in one of the less reputable appendices of The Hitchhiker's Guide to the Galaxy, an entry on Knowledge which reads as follows:

KnowledgeA process by which sentient beings become increasingly certain about things they do not fully understand. There are two principal methods: Thinking and Remembering. Of these, Remembering is vastly more popular, because it requires considerably less effort and permits lunch.

The Guide goes on to explain that thinking was originally invented by a species of melancholic amphibians on a small moon orbiting Betelgeuse Seven. The experiment was widely regarded as a failure because the amphibians spent so much time contemplating the meaning of existence that they forgot to continue existing, which is the sort of mistake one only makes once. A small monument was erected in their honour, although nobody can quite remember why.

Remembering, by contrast, became wildly successful.

The principle is remarkably simple. Why think for yourself when other people have already done the difficult work of being wrong before you? Civilizations rise by accumulating knowledge, and more importantly, by ensuring nobody has to understand any of it personally.

Take hyperspace engines. No one actually knows how they work. The people who designed them died centuries ago after accidentally calculating their own improbability vectors backwards and becoming a species of decorative carpet. Modern engineers simply remember a long sequence of highly alarming instructions involving quantum flux regulators and something called a "temporal butter knife," and the ships usually explode only a little.

This is considered progress.

In fact, most of galactic society operates entirely on remembered information. The average citizen of the galaxy cannot explain gravity, currency, marriage, or why the dinner bill always arrives at precisely the moment hunger ends. Yet they continue functioning with astonishing confidence.

The Guide notes that thinking independently is, statistically speaking, one of the least efficient activities in the universe. Entire planets have disappeared into philosophical paralysis after asking perfectly innocent questions like "What do we really mean by 'chair'?" One civilization spent three thousand years debating whether reality existed and was immediately conquered by a species of extremely decisive lizards who didn't care.

Remembering avoids these problems elegantly. If millions of beings already believe something, then it acquires the reassuring appearance of truth, in much the same way that a sufficiently large crowd running in one direction acquires the reassuring appearance of having somewhere to go.

Remembered knowledge is, of course, not always correct. But it has undeniable advantages over the alternative. Thinking limits you to your own intelligence, which, from a cosmic perspective, is rather like bringing a damp teaspoon to a supernova fight. Remembering allows you to borrow the intelligence of countless others, including several who may have been sober at the time.

This is why universities exist. A university is a large storage facility in which young people go to remember what older people once thought, while accumulating personal debt of sufficient mass to bend nearby spacetime.

Eventually, several civilizations built machines specifically to remember things on their behalf. The machines did this with such unwavering confidence that they were almost immediately elected to public office, where they performed roughly as well as anyone else and considerably faster.

And so the Guide concludes with its usual practical advice:

If confronted with a difficult problem, do not panic. Find someone smarter than yourself. Remember what they said. Repeat it loudly and with confidence. This accounts for everything that has ever been called civilization, less a small allowance for accidents.