Per this NGram, the noun phrase ten men's strength has effectively no currency today compared to the strength of ten men.

But when a builder is estimating the price for your job, it's always That'll be ten hours' work, and never That'll be the work of ten hours.

Is this marked difference in preferred usage something to do with the fact that an "amount of work" is routinely and naturally "quantified" as a multiple of a contextually-appropriate time-span? The preference seems to still apply even when the "multiple" is one - it's always That's a weeks work and He's got the strength of an ox, never That's the work of a week or He's got an ox's strength.

I feel there must be some general principle here rather than just idiomatically established usage, but when considering the ELL question “The stubble of several nights” vs. “several nights' stubble” I realised that although there are many contexts where of and the Saxon genitive (possessive apostrophe) are equivalent and interchangeable, there are also many contexts where the preference for one or the other is very strong (we all know what we say, even if we can't say why).

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    The Ngram nudges slightly higher if you use men's instead of mens'. It's still not enough to reverse your thesis, except for a couple of periods in the 1800s.
    – Lawrence
    Dec 18, 2016 at 14:31
  • I suspect this has something to do with how of is used. In the work of ten men, the work is done by the men. In the work of ten hours, the ten hours is just a measure of the work. Using of in conjunction with measures sounds more archaic to me than using of to describe some quality of the noun phrase that follows.
    – Lawrence
    Dec 18, 2016 at 14:37
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    @Lawrence: Oops! I'd better correct that! It's not a mistake I'd normally be likely to make - I think I must have been affected by the fact that ten mens strength is already "weird" regardless of whether and where you include a possessive, so my "inner grammarian" was feeling a bit discombobulated at the time. Dec 18, 2016 at 14:48
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    First, ten men's strength does not really seem weird to me. But I suspect the preference for the periphrastic genitive here and in translating Beowulf lines 379-81 has to do with our association of epic or mythic contexts (in which alone we encounter this sort of formula about strength) with elevated diction. Dec 18, 2016 at 15:01
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    I believe the only reason "Samson had the strength of ten men" sounds right to us is that we're all familiar with biblical phrasings and our ear hearkens back to those. To say Samson had "ten mens' strength" is somehow more modern, more specific, and less orotund—markedly less biblical.
    – Robusto
    Dec 18, 2016 at 15:02

4 Answers 4


When the possessive apostrophe is used, the word or phrase before it is usually a unit which you can quantify relatively concretely and easily. For example:

A week's work implies it takes around 35 to 40 hours, which depends on where you live, to complete the work. 10 hours' work works in the same way. You can quantify approximately how much you can produce/write/analyze, etc. in a week based on your own experience and get some idea of how much this work would be. Here, we assume the worker is a run-of-the-mill worker/writer/analyst and we don't emphasize how much it takes.

A week's notice implies you need to give a notice a week prior to an action such as resignation letter or contractually mandatory notice, etc. a notice of a week is never wrong, but doesn't sound as idiomatic as a week's notice.

The same logic applies to several nights' stubble. You know how long mustache or beard grows a day based on your experience. Of course, it can be different depending on people's age or hormone level, but the difference is negligible.

However, the strength of ten men is different. You can't quantify 10 men's strength as objectively and easily as 10 hours' work. It's more abstract than concrete as each man has different strength. Also, the purpose of saying he has the strength of ten men is not to quantify his strength approximately, but to emphasize he is very strong. It sounds more like hyperbole with the strength of 10 men's strength combined which is almost impossible to have in the real world.

Samson was said to be so strong that he could uplift two mountains and rub them together like two clods of earth... [Wikipedia article on Samson]

I don't think it represents the strength of just 10 men.


He's got the strength of an ox, never He's got an ox's strength.

I think it depends. If you compare strength of a giant and giant's strength, the Ngram Viewer seems to suggest almost equal number of results.

I think it all depends on how idiomatic the phrase sounds.


In this case, I don't believe this is so much a matter of indicating quantity as it is possession. The strength "belongs" to the ten men. I read the apostrophe as being possessive. For example, "ten men's wives".

At the same time, "ten men's strength" doesn't read as well to me as "strength of ten men" even though I much prefer direct language over the indirect language used in "strength of ten men".


This is awkward because "ten" modifies "men" and then "ten men" modifies "strength". Sometimes this type of structure is desired because it causes your brain to stop for a second and then record the meaning, which can give a richer meaning to the sentence.


I'd like to support and expand on Rathony's answer. As he says, "A man's strength" as a unit of measure would have made sense in an era when an inch was a thumb's width, a foot was, well, a foot, and a mile was a thousand paces. But today it only makes sense to think of units of measure as being based on non-human, non-living solid physical constants. The SI units are defined in formal physics terms and the inch is now officially 1/36 of 0.9144 meter. So I propose that, just as it is no longer current for formal units to be defined in relation to humans, informal units such as "strength" seem less natural to be spoken of in constructions that suggest a human reference point.

This is part of a more general trend. As a scientific way of thinking has increased in popularity and a religious way of thinking has decreased in popularity, there has been a gradual transition from thinking of observed categories (including categories related to humans) as something God-given and blessed with ultimate truth and meaning, to thinking of them as categories that developed according to natural processes. Instead of the planets moving in orbits fixed eternally on solid crystal spheres placed in motion by God at the beginning of time, they are known to move in orbits that follow the laws of physics in their general description, but certainly could have been different in the specifics (and, indeed, are different in other solar systems). Instead of species being created by God and preserved on the Ark through the Deluge, they are constantly evolving and changing in their boundaries.

Likewise, distinctions between categories of humans such as races and sexes were once thought of as having been created by God and therefore absolute in the plan of the universe; whereas today they are more progressively considered to be fluid and socially constructed and there is a de-emphasis of even the degree of solidity that would come from a biological basis. So, in the past, you see human categories used as the "measure of all things". Lands were named after the races who inhabited them, whereas now people are named after the land they come from.

In that vein, "standard" humans were perfectly reasonable to think of as reference points for measures, and in fact were an excellent choice because you always had one at hand when you needed to measure something! But now humans don't seem like good reference points for measures at all, because we think of humans as being diverse and changing.

  • But how does this explain the preference of the Norman genitive over the Saxon in this particular example? Jan 17, 2017 at 0:01
  • Hmm, Rathony seems to be gone. My comment was, as I wrote, intended only to build on that other answer, so it's not as useful without the other answer unfortunately. I'll try to come back and round it out with the missing info. Apr 24, 2017 at 20:10
  • Answers need to be independent and address the original question in full. Addressing other answers may only be done in 'comments'. Apr 24, 2017 at 22:48

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