Studying writing and formal speaking in detail will often bring a certain number to your attention. Without consciously deciding to do so, it is astonishing how often writers and  speakers use patterns of three.

I’ve always been more of a fan of letters than numbers, but it’s interesting to look into the possibilities of mathematics influencing language. Three is a manageable number for the human brain – any more and we start to lose interest, any fewer and we’re left dangling and wanting more.

Consider the following well-known statements, and ask yourself whether they would have become as quotable had their attributors used patterns of two or four.

“I came, I saw, I conquered.” (Julius Caesar)
“Justice, good will and brotherhood.” (Martin Luther King, Jr.)
“Education, education, education.” (Tony Blair)

Would Caesar’s statement have held the same gravity if he had mentioned that he had coins minted with his image on them, or had occasional absence seizures? Would Blair have driven home what his priorities were as prime minister in 1997 if he had just mouthed “education” a couple of times?

The “rule of three”, or “triadic structure” as it is sometimes known, plays a pivotal role in the way we speak and write – not only in content but also in style. Here are some examples of how our interest tends to fade after three:

1. Firstly, secondly, thirdly…

Especially when putting an argument across, it’s very common to see writers take to introducing each paragraph with the words “firstly”, “secondly”, “thirdly”. It’s a very clear and forceful way to put a point forward, and acts as an indication that you’ve moved from one point to the next. Three points is a nice number to settle upon too; it shows that you can back your argument up with a number of points, but you’re not going to bore your reader by going into all of them.

Consider reading a piece that continues with “fourthly”, “fifthly”, “sixthly” etc. Microsoft Word is happy for us to go all the way up to “tenthly” without brandishing its red squiggly line, but I imagine that the piece would start to lose its impact if these –ly endings were used to open every paragraph. If you have that many points to make, it would probably be more advisable to number or bullet point them.

Anything above “thirdly”, while not incorrect as such, is rarely used. Illustrating this, Googling “thirdly” brings up more than five million search results, while “fourthly” produces fewer than 900,000.

2. Once, twice, thrice…

We have words we commonly use to show that we’ve done something one or two times, but what about three? Lionel Richie might never have had a hit with “Thrice a Lady”, and the word always sounds a tad poetic and archaic.

Nevertheless, most of us will understand what it means, and medics will often talk of a “thrice daily” dosage. Can you keep this sequence going, though? Is there a neat little word for doing something four, five or six times?

Oxford Dictionaries says no, and there never has been. Doing something more than three times has obviously never been common enough to require a specific adverb.

3. Primary, secondary, tertiary…

We all went to primary school, then secondary school and the phrase “tertiary education” is sometimes used to describe universities and colleges that provide a third stage of learning, but can we extend this?

Yes, we can on this occasion. “Quaternary” describes a fourth stage, “quinary” a fifth (although Word doesn’t like it) and you can even go as far as the word “duodenary” to refer to the number 12. You’re likely to get blank looks if you use these terms, however, with “tertiary” being the absolute limit of the average Joe’s understanding – suggesting again that we’re out of our comfort zone once we get beyond three.

It probably sums things up that, without even consciously deciding upon it, I’ve sought out three examples of patterns tailing off after three, and three examples of “rule of three” speeches earlier in the article.

Three might not be a crowd, but it appears that any more is when it comes to writing.

John Murray

John is every inch the wordsmith and loves a game of Scrabble above all else. With experience writing for newspapers, John’s time at university was spent studying Creative Writing – something which comes across in his love of the pun.