Genitive of Value & Price
Latin splits worth into two compartments. Indefinite value — what something is reckoned to be worth in judgment — goes in the genitive after verbs of valuing (aestimō, faciō, dūcō, pendō): parvī faciō, "I think little of it." Indefinite price — what something actually costs in a transaction — goes in the ablative after verbs of buying and selling (emō, vendō, cōnstō): vīlī ēmit, "he bought it cheap."
The trap is the overlap. A short list — tantī, quantī, plūris, minōris — keeps the genitive even with buy/sell verbs (quantī ēmit? — "for how much did he buy it?").
Memorize the closed value list (magnī, parvī, plūris, minōris, tantī, quantī, nihilī) and the principle: valuing → genitive; buying → ablative, unless the word is on the overlap list.
Value (how much I rate it) → genitive; price (what was paid) → ablative; four overlap words stay genitive in both.
The value list is closed: magnī, parvī, plūris, minōris, tantī, quantī, nihilī — plus colloquial floccī, assis. Anything outside the list defaults to ablative when paid.
See It In Action
— Sall. Cat. 52. 9
Parvī pendēbātis is the textbook value pattern: a verb of weighing (pendō) plus the bare genitive parvī — "you valued it at little." No preposition, no ablative — the genitive alone carries "how much."
— Sall. Cat. 52. 5
Plūris … fēcistis — faciō in the sense "value" plus the comparative genitive plūris ("at a higher rate"). Notice how naturally the genitive pairs with quam + accusative for a comparison of worth.
— Plin. Ep. ii. 14. 6
Pliny picks the overlap form tantī with cōnstat, "it costs" — a buy/sell verb that would normally take the ablative (magnō cōnstat = "it costs a lot"). Tantī, quantī, plūris, minōris are the four words that always keep the genitive, even on the price side of the line.
Both answer "how much?" — but value is reckoned in the head, price is paid in coin, and the verb decides which case you need.
what it's WORTH (esteemed at)
parvī faciō
I think little of it
what it COST (paid)
vīlī ēmit
he bought it cheap
Tip: Ask: is the verb one of valuing (aestimō, faciō, dūcō, habeō, pendō) or one of buying/selling (emō, vendō, cōnstō, stō, vēneō)? Valuing → genitive. Buying → ablative — except when the word is tantī, quantī, plūris, or minōris, which override and stay genitive.
In Pliny's tantī cōnstat ut sīs disertissimus, why is tantī in the genitive when cōnstō is a buy/sell verb that normally takes the ablative of price?
Study Tips
- •Memorize the seven value genitives as a single chant: magnī, parvī, plūris, minōris, tantī, quantī, nihilī. They're a closed set — anything else won't appear in this construction.
- •When you see emō, vendō, cōnstō, stō, vēneō, expect the price in the ablative (magnō, parvō, vīlī, multō); flip to genitive only when the word is tantī / quantī / plūris / minōris.
- •Translate value-genitives with English value verbs ("I value, I esteem, I care") plus an adverb of degree — parvī faciō = "I think little of," nihilī faciō = "I don't care a bit."