Dative of Purpose

382. The dative is used to denote the purpose or end, often with another dative of the person or thing affected.

This use of the dative, once apparently general, remains in only a few constructions, as follows.

1. The dative of an abstract noun is used to show that for which a thing serves or which it accomplishes, often with another dative of the person or thing affected.
   

   Reī pūblicae clādī sunt. (Iug. 85.43)
   They are ruin to the state.
   (they are for a disaster to the state)

   Māgnō ūsuī nostrīs fuit. (B. G. 4.25)
   It was of great service to our men.
   (to our men for great use)

   Tertiam aciem nostrīs subsidiō mīsit (id. 1.52)
   He sent the third line as a relief to our men.

   Suīs salūtī fuit. (id. 7.50)
   He was the salvation of his men.

   Ēvēnit facile quod dīs cordī esset. (Liv. 1.39)
   That came to pass easily which was desired by the gods.
   (was for a pleasure [lit. heart] to the gods)

   Note 1— This construction is often called the Dative of Service, or the Double Dative construction. The verb is usually sum. The noun expressing the end for which is regularly abstract and singular in number and is never modified by an adjective, except one of degree (māgnus, minor, etc.), or by a genitive.

   Note 2— The word frūgī used as an adjective is a dative of this kind.

   Cōgis mē dīcere inimīcum Frūgī.(Font. 39)
   You compel me to call my enemy Honest.

   hominēs satis fortēs et plānē frūgī (Verr. 3.67)
   men brave enough and thoroughly honest
   [Cf. Erō frūgī bonae. (Plaut. Pseud. 468) I will be good for something. See § 122.b.]

2. The Dative of Purpose of concrete nouns is used in prose in a few military expressions, and with freedom in poetry.
   

   Locum castrīs dēligit. (B. G. 7.16)
   He selects a site for a camp.

   receptuī canere
   to sound a retreat
   (for a retreat)

   receptuī sīgnum (Phil. 13.15)
   the signal for retreat

   Optāvit locum rēgnō. (Aen. 3.109)
   He chose a place for a kingdom.

   locum īnsidiīs circumspectāre (Liv. 21.53)
   to look about for a place for an ambush
   [Cf. locum sēditiōnis quaerere (id. 3.46).]

For the Dative of the Gerundive denoting Purpose, see § 505.b.