Why is "Samson had ten men's strength" non-idiomatic?

Question

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).

Answer 1

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.

However,

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.

Answer 2

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".

Answer 3

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.

Answer 4

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.