of difference_. Sec. 317.

_28._ The ablative of a noun or pronoun with a present or perfect
participle in agreement is used to express attendant circumstance.
This is called the _ablative absolute_. Sec. 381.

_29._ 1. Descriptions of physical characteristics are expressed by the
ablative with a modifying adjective. Sec. 444.

2. Descriptions involving neither numerical statements nor physical
characteristics may be expressed by either the genitive or the
ablative with a modifying adjective. Sec. 445.

_30._ The ablative is used to denote _in what respect_ something is
true. Sec. 398.

_31._ The _place from which_ is expressed by /a\ or /ab\, /de:\, /e:\
or /ex\ with the separative ablative. This answers the question
Whence? Before names of towns, small islands, /domus\, and /rus\ the
preposition is omitted. Secs. 264, 266.

_32._ Words expressing separation or deprivation require an ablative
to complete their meaning. This is called the _ablative of
separation_. Sec. 180.

_33._ The word expressing the person from whom an action starts, when
not the subject, is put in the ablative with the preposition /a\ or
/ab\. This is called the _ablative of the personal agent_. Sec. 181.

_34._ The comparative degree, if /quam\ is omitted, is followed by the
separative ablative. Sec. 309.

_35._ The _time when or within which_ anything happens is expressed by
the ablative without a preposition. Sec. 275.

_36._ 1. The _place at or in which_ is expressed by the ablative with
/in\. This answers the question Where? Before names of towns, small
islands, and /rus\ the preposition is omitted. Secs. 265, 266.

2. Names of towns and small islands, if singular and of the first or
second declension, and the word /domus\ express the _place in which_
by the locative. Sec. 268.

_Gerund and Gerundive_

_37._ 1. The gerund is a verbal noun and is used only in the genitive,
dative, accusative, and ablative singular. The constructions of
these cases are in general the same as those of other nouns. Sec.
406.1.

2. The gerundive is a verbal adjective and must be used instead of
gerund + object, excepting in the genitive and in the ablative
without a preposition. Even in these instances the gerundive
construction is more usual. Sec. 406.2.

_38._ The accusative of the gerund or gerundive with /ad\, or the
genitive with