The idiom, “in a nutshell” is used when you want to say that the description you’re giving is concise, to-the-point and brief. It is the information boiled down to its simplest form. The question is: where do nuts enter this equation?
In a nutshell origin
It is thought that the first use of the phrase “in a nutshell” was a literal one. It was used by Pliny the Elder around the 1st century AD. In the text, Pliny’s Natural History – Book 7, (xxi 85), Pliny tells us that fellow famous Roman, Cicero told him that he saw a copy of the famous poem, Homer’s Iliad, being miniaturized so that the whole text, written on tiny parchment, could fit into a walnut shell. Why would anyone do such a thing? Some people have unique hobbies. My guess is that they probably do it for the mere challenge and satisfaction of success that it brings.
In any case, throughout history this incredible feat was repeated with various other texts being miniaturized including the Bible. Later one man named Huet, Bishop of Avranches, tested the miniaturization of the Iliad, fitting the whole thing onto a piece of parchment sized 27cm x 21cm. To achieve this he had to write 80 verses of poetry in a single line! When the final paper was filled with minute writing and was folded up, it could indeed fit in a nutshell.
Although this is all very interesting, copying the whole of the Iliad in full detail is a far cry from how we’d describe the Iliad “in a nutshell” today. Using today’s phrase, the Iliad in a nutshell would be written in an abbreviated, shortened form, where the text would only contain the paraphrased, brief, main gist of it. So how did the phrase “in a nutshell” come to mean “brief and concise”?
The idea of having a detailed amount of information containing all the facts, neatly contained in a small, compact nutshell somehow evolved into the idea of having *just* the facts you need, minus the superfluous waffle. In a nutshell gradually became connected to the idea of the information itself become compacted.
So next time you’re writing something “in a nutshell” you can be glad that you’re writing it according to today’s interpretation of the phrase rather than literally squeezing your words into a nut!
Ayto J. 2000. Brewer’s Dictionary of Phrase and Fable. Collins; 16th edition
Forsyth M. 2011. The Etymologicon. Icon Books