Secs. 524, 525.

_441._ Observe the English sentences

(1) _A man /of\ great courage_, or (2) _A man /with\ great courage_

(3) _A forest /of\ tall trees_, or (4) _A forest /with\ tall trees_

Each of these sentences contains a phrase of quality or description.
In the first two a man is described; in the last two a forest. The
descriptive phrases are introduced by the prepositions _of_ and _with_.

In Latin the expression of quality or description is very similar.

The prepositions _of_ and _with_ suggest the genitive and the ablative
respectively, and we translate the sentences above

(1) /Vir magnae virtutis\, or (2) /Vir magna virtute\
(3) /Silva altarum arborum\, or (4) /Silva altis arboribus\

There is, however, one important difference between the Latin and the
English. In English we may say, for example, _a man of courage_, using
the descriptive phrase without an adjective modifier. _In Latin,
however, an adjective modifier must always be used_, as above.

_a._ Latin makes a distinction between the use of the two cases in
that _numerical descriptions of measure are in the genitive_ and
_descriptions of physical characteristics are in the ablative._
Other descriptive phrases may be in either case.

_442._ EXAMPLES

1. Fossa duodecim pedum, _a ditch of twelve feet_.

2. Homo magnis pedibus et parvo capite,
_a man with big feet and a small head_.

3. /Rex erat vir summa audacia\ or /rex erat vir summae audaciae\,
_the king was a man of the greatest boldness_.

_443._ RULE. Genitive of Description. _Numerical descriptions of
measure are expressed by the genitive with a modifying adjective._

_444._ RULE. Ablative of Description. _Descriptions of physical
characteristics are expressed by the ablative with a modifying
adjective._

_445._ RULE. Genitive or Ablative of Description. _Descriptions
involving neither numerical statements nor physical characteristics may
be expressed by either the genitive or the ablative with a modifying
adjective._

_446._ IDIOMS

Helvetiis in animo est, _the Helvetii intend_,
(lit. _it is in mind to the Helvetians_)
in matrimonium dare, _to give in marriage_
nihil posse, _to have no power_
fossam perducere, _to construct a ditch_
(lit. _to lead a ditch through_)

_447._ EXERCISES

I. 1. Milites fossam decem pedum per eorum finis perduxerunt.
2. Princeps Helvetiorum, vir summae audaciae, principibus gentium
f