The interpretation timeline
Joel 2:23 Douay-Rheims

And you, O children of Sion, rejoice, and be joyful in the Lord your God: because he hath given you a teacher of justice, and he will make the early and the latter rain to come down to you as in the beginning.

1105 – 1871 4 witnesses

Scholastic

c. 1100 – 1500
1105
A.D.
Rashi Jewish
1040–1105
“the teacher for justification Heb. מוֹרֶה. Your prophets who teach you to return to Me, in order to justify you. the early rain and the late rain. Heb. מוֹרֶה, like (Deut. 11:14) “the early rain (יוֹרֶה) and the late rain (וּמַלְקוֹֹש).” in the first month—In Nissan. Although the early rain is the first rain, which falls on the seeds, and that is in Marcheshvan, that year they sowed in Nissan, as is explained in Tractate Taanith (5a) that the grain grew in eleven days.”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Be glad then, ye children of Zion,.... The people of the Jews, and especially the spiritual and believing part of them; such as were born again, that were born of Zion, and born in Zion, and brought up by her, and in her; the children of that Zion or Jerusalem that is the mother of us all; and who were looking for the Messiah, and to whom it would be good news and glad tidings to hear of his coming, Zac 9:9; and rejoice in the Lord your God; not in any creature or creature enjoyment, but in the Lord. The Targum is, "in the Word of the Lord your God;'' in Christ the essential Word; see Phi 3:3; though rather Jehovah the Father, the giver and sender of Christ, is here meant, because of what follows; and who is to be rejoiced in by his people, not as an absolute God, but as in Christ, and as their covenant God and Father in him; who has chosen them for himself, and is their portion and inheritance; which are reasons sufficient why they should rejoice in him, and others follow: for he hath given you the former rain moderately; or rather, "for he hath given you the teacher of righteousness" (g); to which agrees the Targum, "for he hath returned to you your teacher in righteousness;'' and so Jarchi paraphrases the words, and interprets them of the prophets in general, "your prophets that teach you to return unto me, that I may justify you;'' and R. Japhet says that signifies a prophet that should teach them in the way of righteousness; not Isaiah, as Grotius; but the King Messiah as Abarbinel interprets it; who is the teacher sent from God, and given by him, as his presence with him, and the miracles done by him, sufficiently prove, Joh 3:2; for which he was abundantly qualified, being the omniscient God, and the Son of God that lay in the bosom of his Father; is the Wisdom of God, as Mediator; had the Spirit of wisdom on him, and the treasures of wisdom and knowledge hid in him; and who is able to make his teachings effectual, and to qualify others for such work. This office he performed personally on earth, both in a doctrinal way, and by way of example; and now executes it by his Spirit, and by his ministers: and a "teacher of righteousness" he may be truly said to be; since he not only taught the Gospel, the word of righteousness in general; but in particular directed men to seek in the first place the righteousness of God, which is no other than his own; and pronounced those happy that hungered after it: he declared he came to fulfil all righteousness, even the law for righteousness; and taught men to believe in him for it, and to live righteously and godly. Aben Ezra observes, that the phrase is the same with "the sun of righteousness", Mal 4:2; which is said of Christ the author of righteousness, who is our righteousness made so by imputation, the Lord our righteousness: or, as here, "a teacher unto, or for righteousness" (h), all which is matter of joy and gladness; see Isa 61:10; and he will cause to come down for you the rain, the former rain, and the latter rain in the first month; alluding to the two seasons of the year in which rain was given to the Jews; the former rain fell in Marchesvan, which answers to our September and, October, part of each, at their seedtime; and the latter in Nisan, the first month of their ecclesiastical year, and answers to part of March and April, and fell some time before their harvest; and these former and latter rains now fall about the same time. So Dr. Shaw (i) observes, that "the first rains in these countries (Syria, Phoenicia, and the Holy Land) usually fall about the beginning of November; the latter sometimes in the middle, sometimes toward the end, of April:'' and elsewhere he says (k), "in Barbary the first rains fall some years in September, in others a month later; the latter rains usually fall in the middle of April:'' and the same traveller relates (l), that "upon the coast (of Egypt) from Alexandria, all along to Damiata and Tineh, they have their former and latter rains as in Barbary and the Holy Land.'' This rain spiritually designs the doctrine of the Gospel, which is sometimes compared to rain, Deu 32:2; because as rain it comes from God, descends from heaven, is a divine gift, both as to the ministry and experience of it; it tarries not for man, neither for his desires nor deserts; falls according to divine direction, sometimes here, and sometimes there; is a great blessing, and brings many with it, revives, refreshes, and makes fruitful. Jerom interprets these two rains of the first receiving of doctrine, and of a more perfect knowledge of it; as also of the two Testaments, the Old and New: but it may be better interpreted of the preaching of the Gospel by John the Baptist, and by Christ; or by Christ, and then by his apostles; or of the first and second ministration of apostles, first to the Jews, then to the Gentiles; or of the coming of Christ in the flesh, for the same word is used here as in the former clause, and of his spiritual coming in the latter day, both which are compared to rain, Hos 6:3. (g) "doctorem justitiae", V. L. Pagninus, Montanus, Munster. (h) "Doctorem ad justitiam", Tigurine version, Mercerus, Castalio, Drusius, Cocceius, Burkius. (i) Travels, tom. 2. par. 2. c. 1. p. 335. Ed. 2. (k) Ib. tom. 1. part 3. sect. 2. p. 137. (l) Ib. tom. 2. part 2. c. 2. sect. 3. p. 377.”
Source
1849
A.D.
1774–1849
“Teacher; Joel, &c., or rather the Messias, John i. 9., and Matthew xxiii. 8. Some translate Hebrew, “rain.” Septuagint, “meat,” (Calmet) sufficient for the people. (Theodoret) — Rain . Osee vi. 3.”
1871
A.D.
1871
“rejoice in the Lord--not merely in the springing pastures, as the brute "beasts" which cannot raise their thoughts higher (Isa 61:10; Hab 3:18). former rain . . . the rain . . . the former . . . the latter rain--The autumnal, or "former rain," from the middle of October to the middle of December, is put first, as Joel prophesies in summer when the locusts' invasion took place, and therefore looks to the time of early sowing in autumn, when the autumnal rain was indispensably required. Next, "the rain," generically, literally, "the showering" or "heavy rain." Next, the two species of the latter, "the former and the latter rain" (in March and April). The repetition of the "former rain" implies that He will give it not merely for the exigence of that particular season when Joel spake, but also for the future in the regular course of nature, the autumn and the spring rain; the former being put first, in the order of nature, as being required for the sowing in autumn, as the latter is required in spring for maturing the young crop. The Margin, "a teacher of righteousness," is wrong. For the same Hebrew word is translated "former rain" in the next sentence, and cannot therefore be differently translated here. Besides, Joel begins with the inferior and temporal blessings, and not till Joe 2:28 proceeds to the higher and spiritual ones, of which the former are the pledge. moderately--rather, "in due measure," as much as the land requires; literally, "according to right"; neither too much nor too little, either of which extremes would hurt the crop (compare Deu 11:14; Pro 16:15; Jer 5:24; see on Hos 6:3). The phrase, "in due measure," in this clause is parallel to "in the first month," in the last clause (that is, "in the month when first it is needed," each rain in its proper season). Heretofore the just or right order of nature has been interrupted through your sin; now God will restore it. See my Introduction to Joel.”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.