1175. The dative denotes that for or to which a thing is or is done, and
either accompanies single words, such as verbs, adjectives, sometimes
adverbs, rarely substantives, or serves to modify the entire sentence.
It has two principal uses.
1176. I. The dative is used as a complement. Complements may be roughly
distinguished as essential or optional. But these two complements are
not always separated by a sharp line, and the same dative may sometimes
be referred indifferently to either head.
1177. (1.) The ESSENTIAL COMPLEMENT is a dative of the person or thing
added to an idea which is felt as incomplete without the dative (1180).
Thus, #pāret#, _he is obedient_, is a statement which is felt as
incomplete without a dative added to denote what it is he is obedient
to, in the sentence #pāret senātuī#, _he is obedient to the senate_. But
when stress is put on the action merely, without reference to its
bearing, such a verb may be used without a dative: as, #pāret#, _he is
obedient_, _he yields obedience_.
1178. (2.) The OPTIONAL COMPLEMENT, that is, the dative of interest,
advantage, or disadvantage, adds something to an idea that is already
complete in itself (1205).
Thus, #carmina cantō#, _I chant verses_, is a statement entirely
complete in itself; it may be modified or not, at option, by a dative,
thus: #carmina virginibus puerīsque cantō#, _verses for maids and boys I
chant_.
1179. II. The dative of certain substantives is used predicatively
(1219).