78. Instrum. of time.

III. The instrumental of time serves to denote in what time something is accomplished. {P. 2, 3, 6.} Not rarely this conception coincides with that of the time, after which something is happening. māsenānuvāko ’dhītaḥ (the chapter was learned in (after) a month).

The same applies to space. krośenānuvāko ’dhītaḥ (*1).

Examples: Panc. 2 dvādaśabhir varṣair vyākaraṇaṃ śrūyate (v. a. grammar requires twelve years to be mastered), ibid. 237 katipayair evāhobhir mayūra iva sa balavān saṃvṛttaḥ (in a few days he [the crow] grew strong like a peacock), Daç. 159 tato ’lpīyasā kālena rājñaḥ priymahiṣyekaṃ putramasūta (after some time the king's chief queen was delivered of a son), R. 1, 13, 35 tataḥ kaiścid ahorātrair upayātāḥ mahīkṣitaḥ, Panc. 282 tayor vrajatoryājanadvayamātreṇāgrataḥ kācinnadī samupasthitā (as they went on, after no more than two yojanas the couple came in sight of some river). So dinaiḥ, divasaiḥ etc. — »in process of time."

Rem. 1. The fundamental conception seems here to be that of concomitancy. Hence it may be explained, how the third case occasionally denotes even at what time, as R. I, 72, 12 ekāhnā (at one and the same day) rājaputrīṇāṃ catasḥṇāṃ pāṇīngṛhṇantu catvāro rājaputrā, and such standing phrases as tena kālena, tena samayena which are especially frequent in Buddhistic and Jain books.

Rem. 2. The naxatra or constellation, under which something occurs, may be put indifferently in the third or the seventh case {P. 2, 3, 45. cp. 4, 2, 4.}: puṣyeṇa or puṣye pāyasamaśnīyāt. Examples of the instrum. Âçv. Grhy. 3, 5, 1 athāto ‘dhyāyopākaraṇamoṣdhīnāṃ prādurbhāve śravaṇena…hastena vā, Pat. I, 231 katareṇa tiṣyeṇa gataḥ

(*1)
The difference between this instrum. of time and the above mentioned acc. of time (54) is illustrated by these examples of the Kaçikâ: It is said māsenā(krośena) 'nuvāko 'dhītaḥ, but māsam adhīto 'nuvāko na cānena gṛhītaḥ, for »if the subject ceases the action before having reached its aim, the instrumental may not be employed."

78. 時間のinst.

III. 時間を表すinst.は、行為がいつ遂行されるかを記述することに資する。この概念が「今より後の、何事かの起こっている時間」と一致することがよくある。māsenānuvāko ’dhītaḥ (the chapter was learned in (after) a month)

同じことが空間にも適用される。krośenānuvāko ’dhītaḥ（*1）

例：
Panc. 2 dvādaśabhir varṣair vyākaraṇaṃ śrūyate (v. a. grammar requires twelve years to be mastered)
ibid. 237 katipayair evāhobhir mayūra iva sa balavān saṃvṛttaḥ (in a few days he [the crow] grew strong like a peacock)
Daç. 159 tato ’lpīyasā kālena rājñaḥ priymahiṣyekaṃ putramasūta (after some time the king's chief queen was delivered of a son)
R. 1, 13, 35 tataḥ kaiścid ahorātrair upayātāḥ mahīkṣitaḥ, Panc. 282 tayor vrajatoryājanadvayamātreṇāgrataḥ kācin nadī samupasthitā (as they went on, after no more than two yojanas the couple came in sight of some river)

よってdinaiḥ、divasaiḥ等は「時が経つにつれて」となる。

【補足1】
ここでの〔inst.の〕根本をなす概念は、「付随」のようである。よって以下の例のように、「…の時に」さえもinst.で表されることがある。
R. 1, 72, 12 ekāhnā (at one and the same day) rājaputrīṇāṃ catasḥṇāṃ pāṇīngṛhṇantu catvāro rājaputrā

以下のような、仏教やジャイナ教の文献に殊に頻出するtena kālena, tena samayenaのような定型句も同様。

【補足2】
その下でなにがしかが起こるような星宿（nakṣatra）は、無規則にinst.やloc.で置かれる：〈puṣyeṇa / puṣye〉 pāyasamaśnīyāt。inst.の例は以下の通り。
Âçv. Grhy. 3, 5, 1 athāto ‘dhyāyopākaraṇamoṣdhīnāṃ prādurbhāve śravaṇena…hastena vā
Pat. I, 231 katareṇa tiṣyeṇa gataḥ

（*1）
時間を表すinst.と、上述の時間を表すacc.（54）との違いは、これらのKaç.（on P. 2, 3, 6）の例で例証できる：〔inst.だと〕māsenā (krośena) 'nuvāko 'dhītaḥとなるが、「主語が、目標に達する前に行為を中止した場合、inst.は用いられない」ので、〔その場合は〕māsam adhīto 'nuvāko na cānena gṛhītaḥとなる。