to denote purpose; as,--

homo ad agendum natus est, _man is born for action_.

4. Ablative. The Ablative of the Gerund is used--

a) Without a Preposition, as an Ablative of Means, Cause, etc. (see Sec.
218, 219); as,--

mens discendo alitur et cogitando, _the mind is nourished by learning
and reflection_.

Themistocles maritimos praedones consectando mare tutum reddidit,
_Themistocles made the sea safe by following up the pirates_.

b) After the prepositions a, de, ex, in; as,--

summa voluptas ex discendo capitur, _the keenest pleasure is derived
from learning_;

multa de bene beateque vivendo a Platone disputata sunt, _there was
much discussion by Plato on the subject of living well and happily_.

5. As a rule, only the Genitive of the Gerund and the Ablative (without a
preposition) admit a Direct Object.

Gerundive Construction instead of the Gerund.

339. 1. Instead of the Genitive or Ablative of the Gerund with a Direct
Object, another construction _may be, and very often is, used_. This
consists in putting the Direct Object in the case of the Gerund (Gen. or
Abl.) and using the Gerundive in agreement with it. This is called the
Gerundive Construction. Thus:--

GERUND CONSTRUCTION. GERUNDIVE CONSTRUCTION.
cupidus urbem videndi, _desirous of cupidus urbis videndae;
seeing the city_.
delector oratores legendo, _I am delector oratoribus legendis
charmed with reading the orators_.

2. The Gerundive Construction _must be used_ to avoid a Direct Object with
the Dative of the Gerund, or with a case dependent upon a Preposition;
as,--

locus castris muniendis aptus, _a place adapted to fortifying a camp_;

ad pacem petendam venerunt, _they came to ask peace_;

multum temporis consumo in legendis poetis, _I spend much time in
reading the poets_.

3. In order to avoid ambiguity (see Sec. 236, 2), the Gerundive Construction
must not be employed in case of Neuter Adjectives used substantively. Thus
regularly--

philosophi cupidi sunt verum investigandi, _philosophers are eager for
discovering truth_ (rarely veri investigandi);

studium plura cognoscendi, _a desire of knowing more_ (not plurium
cognoscendorum).

4. From the nature of the case only Transitive Verbs can be used in the
Gerundive construction; but utor, fruor, fungor, potior (originally
transitive) regularly admit it; as,--