Horace, Satires, vol. II, no. 3, l. 74
si male rem gerere insani est, contra bene sani
Translation:
if to manage the thing badly is insane; conversely, if well, it is sane.
insani and sani are instances of the genitive. I feel that I’ve studied this use, but I can’t call forth the grammatical term for it.
I want to say that esse + genitive may mean, “belongs to the category of .” However, I haven’t found an on-point example linked to a precept.
hominis insani.
X is characteristic of one who is Y
Other cases are also well attested. The same Horace for instance says “Miserarum est [non] amori dare ludum.” - It is characteristic of miserable girls not to play at love, i.e., miserable girls can’t love.
This is the so-called genetiuus proprietatis (‘genitive of characteristic quality’). It is used with esse and denotes ‘a person or thing, to which something is suitable, appropriate, characteristic, habitual, assigned, duty, obligation, right etc., often with infinitive as subject’.
These examples are from grammar:
Non huius temporis est ista oratio. ‘This speech is not becoming to our time’
Meae dignitatis non est id facere. ‘To do so is beyond my dignity’
Hoc moris Graecorum est. ‘This is Greek custom’ (This belongs to the custom of the Greeks)
Officii est — — ‘The duty demands that — —’
Regis est imperare, ciuium parere. ‘It behoves king to rule, citizens to obey’
Virorum fortium est sine gemitu dolorem pati. ‘It is appropriate for brave men to bear pain without wail’
Thanks to anphph, and Timothee.
In M&F it’s called the “genitive of description”.
Thanks to rothbard for pointing me to Moreland and Fleischer. I found a helpful example under D. Predicate Genitive (Genitive of Characteristic), in Unit 11 of my book.
M&F example:
Boni est deos laudare.
Translation: It is (the mark) of a good [man] to praise the gods.
My original quotation, edited:
. . . male rem gerere insani est. . . .
Translation: It is (the mark) of a crazy [man] to manage things badly.
These two quotations seem to match very well.
I thought that there were some helpful examples in my reply too, though I can appreciate that sometimes some material for some reason just ‘clicks’ and seems very intuitive. But it is a nice construction, isn’t it? Useful for one’s own composition too, I should think.
Oh, yes, Timothée, those examples were excellent, and I thank you for taking the trouble.
But I wanted to show rothbard where in M&F I found an example I thought perfectly on point. By doing this, I provided an opening for comment in case I misunderstood the example I cited.