The interpretation timeline
1 Corinthians 5:6 Douay-Rheims

Your glorying is not good. Know you not that a little leaven corrupteth the whole lump?

A.D. 202 – 1871 10 witnesses 11 excerpts

Patristic

before A.D. 750
202
A.D.
Irenaeus Patristic
c. A.D. 130–202
“And we have the precept: "If any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner, with such an one no not to eat." And again does the apostle say, "Let no man deceive you with vain words; for because of these things cometh the wrath of God upon the sons of mistrust. Be not ye therefore partakers with them." And as then the condemnation of sinners extended to others who approved of them, and joined in their society; so also is it the case at present, that "a little leaven leaveneth the whole lump." And as the wrath of God did then descend upon the unrighteous, here also does the apostle likewise say: "For the wrath of God shall be revealed from heaven against all ungodliness and unrighteousness of those men who hold back the truth in unrighteousness."”
Source
220
A.D.
Tertullian Patristic
c. A.D. 150–220
“Are women who think that, in furnishing to their neighbour that which is demanded of beauty, they are furnishing it to themselves also, to augment that (beauty) when (naturally) given them, and to strive after it when not (thus) given? Some one will say, "Why, then, if voluptuousness be shut out and chastity let in, may (we) not enjoy the praise of beauty alone, and glory in a bodily good? "Let whoever finds pleasure in "glorying in the flesh" see to that.”
Source
“It remains, therefore, that his meaning was, that that spirit which is accounted to exist in the Church must be presented "saved," that is, untainted by the contagion of impurities in the day of the Lord, by the ejection of the incestuous fornicator; if, that is, he subjoins: "Know ye not, that a little leaven spoileth the savour of the whole lump? " And yet incestuous fornication was not a little, but a large, leaven.”
Source
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“Then, having ended his sentence, and spoken it in brief without dwelling on it, he brings in again a rebuke, directing himself against them; "Your glorying is not good:" signifying that it was they up to the present time who had hindered him from repenting, by taking pride in him. Next he shews that he is taking this step in order to spare not that person only, but also those to whom he writes. To which effect he adds, "Know ye not, that a little leaven leaveneth the whole lump?" "For," saith he, "though the offence be his, yet if neglected it hath power to waste the rest of the body of the Church also. For when the first transgressor escapes punishment, speedily will others also commit the same faults." In these words he indicates moreover that their struggle and their danger is for the whole Church, not for any one person. For which purpose he needeth also the similitude of the leaven. For "as that," saith he, "though it be but little, transforms unto its own nature the whole lump; so also this man, if he be let go unpunished and this sin turn out unavenged, will corrupt likewise all the rest."”
Source

Scholastic

c. 1100 – 1500
1272
A.D.
Thomas Aquinas Catholic
1225–1274
“Above, the Apostle recalled a twofold fault: namely, that of the fornicating Corinthian, and of the others who were tolerating his sin; here he rebukes both faults. First, the fault of those tolerating his sin; second, the fault of the fornicator, there: "the body however is not for fornication," etc. Concerning the first he does two things. First, he rebukes in the Corinthians the negligence of judgment; second, he rebukes in them certain other vices concerning judgment, chapter VI: "does anyone dare," etc. Concerning the first he does two things. First, he rebukes those who did not separate the fornicator from themselves; second, he refutes the false understanding which they had conceived from his words, there: "I wrote to you in the epistle," etc. Concerning the first he does two things. First, he reproves what they had done; second, he shows what is to be done, there: "purge out the old leaven," etc. Concerning the first he does two things. First, he reproves the past fault as to its root. For he had said above that from their being puffed up there follows in them a lack of compassion, and from the lack of compassion, negligence of correction. First, therefore, he argues against the elation of the Corinthians, saying, "your boasting is not good," namely, by which you boast in the defects of others, as though you yourselves were innocent. For each one ought to glory in the Lord concerning the goods divinely given to himself, not concerning others, according to that word of Gal. VI, 4: "but let each one prove his own work, and so he will have glory in himself, and not in another." But it is especially evil to glory in the evils of others. For it is said in Ps. LI, 3: "why do you glory in malice?" Second, he assigns the reason for what he had said, saying, "do you not know that a little leaven corrupts the whole lump?" As if to say: you cannot be ignorant of this. Now it must be known that two things can be considered in leaven. First, the flavor which it gives to the bread, and according to this, by leaven is signified the wisdom of God, through which all the things that belong to man are made flavorful; and according to this it is said in Matth. XIII, 33: "the kingdom of heaven is like leaven, which a woman took and hid in three measures of flour, until the whole was leavened." Second, corruption can be considered in leaven, and according to this, by leaven can be understood, in one way, sin, because indeed through one sin of a man all his works are rendered corrupt, as for instance through the sin of pretense, which is compared to leaven. Lc. XII, 1: "beware of the leaven of the Pharisees, which is hypocrisy." In another way, by leaven can be understood the sinful man, and it is to this that this comparison is brought in. For just as through a little leaven the whole mass of dough is corrupted, so through one sinner the whole society is defiled. Hence Eccli. XI, 34: "from one spark the fire is increased, and from one deceitful man blood is increased." And this indeed happens, when through the sin of one, others are in some way provoked to sin. Or also when they consent to the one sinning, at least by not correcting him when they are able to correct, according to that word of Rom. I, 32: "they are worthy of death, not only they who do these things, but also they who consent to those doing them." And therefore the Corinthians ought not to glory in the sin of one, but rather to take care lest, through the sin of one, all be defiled by association with him, according to that word of Cant. II, 2: "as the lily among thorns, so is my beloved among the daughters," where the Gloss says: "he was not good, who could not tolerate the wicked." Then, when he says, "purge out the old leaven," he shows what is to be done for the rest. And first he sets down the teaching; second he assigns the reason, there: "our Passover," etc. He says therefore first: because "a little leaven corrupts the whole lump," therefore "purge out the old leaven," that is, purge yourselves, by casting away from you the old leaven, that is, the fornicator, who by sinning has returned to the oldness of ancient corruption, according to that word of Baruch III, 11: "you have grown old in a foreign land, you have been defiled with the dead." Which indeed he says, because through the separation of one sinner the whole society is purged. Hence also, when Judas had gone out, the Lord said, Io. XIII, 31: "now is the Son of man glorified." By the old leaven can also be understood ancient error, according to that word of Is. XXVI, 3: "the old error has departed," or also the corruption of original sin, according to that word of Rom. VI, 6: "our old man has been crucified together with him," or also any actual sin whatsoever, according to that word of Col. III, 9: "stripping yourselves of the old man with his deeds": for by the admonition of these a man is purged. He then sets down consequently the effect of the purging, saying, "that you may be a new mixture." Now "mixture" is said to be the commingling of water and new flour, before leaven is mixed in. Therefore, with the leaven removed from the faithful, that is, the sinner, or the sin, they remain as a new mixture, that is, in the purity of their newness, according to that word of Ps. CII, 5: "your youth will be renewed like the eagle's"; Eph. IV, v. 23: "be renewed in the spirit of your mind." Then he sets down the due manner of the purging when he says, "as you are unleavened," that is, without the leaven of sin. For it is said from "a," which is "without," and "zyma," which is "leaven." Hence the Lord, Matth. XVI, 6, says to the disciples, "beware of the leaven of the Pharisees and Sadducees." Then, when he says, "for indeed our Passover," he assigns the reason for what he had said, namely why the faithful ought to be unleavened, which reason indeed is taken from the mystery of Christ's passion. Hence first he sets forth the mystery itself; second he concludes his proposition, there: "therefore let us feast," etc. Concerning the first it must be considered that among the other sacraments of the law the most celebrated was the paschal lamb, which, as is commanded in Ex. XII, 1 ff., was immolated by the whole multitude of the sons of Israel in memory of that benefit, by which the Angel striking the firstborn of Egypt passed over the houses of the Jews, whose doors had been smeared with the blood of the lamb. Hence the name of Pasch is taken, according to what is said there: "for it is the phase," that is, "the passing over of the Lord"; and finally by the power of this benefit the people crossed the Red Sea, as is said in Ex. XIV, 15 ff. For that lamb was a figure of the innocent Christ, of whom it is said, Io. I, 29: "behold the Lamb of God." Therefore, just as that figural lamb was immolated by the sons of Israel, that the people of God might be freed from the striking Angel, and that they might cross the Red Sea, freed from the servitude of Egypt, so Christ was slain by the sons of Israel, through whose blood the people of God is freed from the assault of the Devil and from the servitude of sin, through Baptism as through the Red Sea. That figural lamb, however, was called the Pasch of the Jews, because it was immolated as a sign of the passing over. Hence it is said, Matth. XXVI, 17: "where do you wish that we prepare for you to eat the Pasch?" That is, the paschal lamb. The Apostle says therefore: for this reason you ought to be unleavened, "for indeed," that is, because, just as the figural Pasch of the old people is the lamb immolated, so "our Passover," that is, of the new people, "is Christ, immolated," to whose immolation also the name of Pasch is fitting, both by the signification of the Hebrew tongue, which signifies passing-over, Ex. XII, 11: "for it is the phase," that is, "the passing over," and by the signification of the Greek tongue, insofar as the name Pasch signifies passion. For Christ, through the passion by which he was immolated, passed over from this world to the Father, as is said in Io. XIII, 1. Then, when he says, "therefore let us feast," he concludes his proposition. For the evidence of this it must be considered that, as is read in Ex. XII, 8, the paschal lamb after its immolation was eaten with unleavened breads. Therefore, just as the figural lamb was a figure of our immolated Passover, so the figural paschal observance ought to be conformed to the observance of the new Passover. Therefore, because Christ immolated is our Passover, "therefore let us feast," namely, eating Christ, not only sacramentally, according to that word of Io. VI, v. 54: "unless you eat the flesh of the Son of man, and drink his blood, you will not have life in you," but also spiritually, by enjoying his wisdom, according to that word of Eccli. XXIV, v. 29: "they who eat me shall still hunger, and they who drink me shall still thirst," and thus with spiritual joy, according to that word of Ps. XLI, 5: "with the voice of exultation and confession, the sound of one feasting." Then he determines the manner of feasting according to the conformity of the truth to the figure, saying, "not in the old leaven, nor in the leaven of malice and wickedness." For it was commanded in Ex. XII, 15, that no leaven at all should be found in the houses of those eating the paschal lamb. Leaven, however, has both oldness and corruption. Hence by the removal of leaven, first indeed can be understood the removal of the observance of the precepts of the old law, which through the passion of Christ has been put to death, according to that word of Lev. c. XXVI, 10: "you will cast away the old things, when the new come upon you." Second, by the removal of leaven can be understood the removal of the corruption of sin, as was said above, that "a little leaven corrupts the whole lump." And as to this he adds, "nor in the leaven of malice and wickedness," so that malice is referred to the perversity of the deed, according to that word of Iac. I, v. 21: "casting away all filthiness and abundance of malice." By wickedness, however, is understood fraudulent scheming. Prov. XXVI, v. 25: "when he shall have taken up his voice, do not believe him, for there are seven wickednesses in his heart." Or, according to the Gloss, when he says, "not in the old leaven," he removes the oldness of sin in common. But what he adds, "nor in the leaven of malice and wickedness," explains sin part by part, so that malice is said to be the sin which is committed against oneself, wickedness the sin which is committed against another. Having therefore excluded the undue manner of feasting, he determines the fitting manner, adding, "but in the unleavened bread of sincerity and truth," that is, in sincerity and truth, which are signified by the unleavened bread. Now sincerity is set against the corruption of sin, which he signified when he said, "not in the leaven of malice and wickedness." For that is called sincere which is without corruption. Hence in II Cor. II, 17 it is said: "we are not like many, adulterating the word of God, but from sincerity we speak in Christ." Truth, however, is set against the figures of the old law, as in Io. I, v. 17 it is said, "truth and grace was made through Jesus Christ," because indeed we ought to celebrate the true Passover with truth and not with figures. Hence, according to the Gloss, by sincerity is understood innocence from vices, or newness of life; by truth, however, the justice of good works, or rectitude, which excludes fraud.”

Reformation

c. 1500 – 1650
1637
A.D.
1567–1637
“Your glorying is not good. Your boasting yourselves in your worldly wisdom, which makes you say, 44 1 am of Paul,” 44 1 of Apollos,” is evil and out of place. It were better for you to cast down the eyes of your mind, since you allow so great a wickedness to exist among you. So Anselm ; Theophylact adds from Chrysostom: “He implies obscurely and in a homely way that the Corinthians themselves prevented this fornicator from coming to a better mind, by glorying in his name ; for he was one of their wise teachers” A little leaven leavenefh the whole lump . As yeast penetrates every part of a mass of dough with its taste and sharpness, so does this one taint of the fornicator penetrate and stain all of you: firstly, because for the sake of one man the wrath of God may be kindled against you all, and against the whole Church which suffers him, as Ambrose and Anselm say ; and secondly, if this man go unpunished, others may follow his example, and this one may cause many to stumble. So S. Chrysostom. In other words, remove this scandal, and separate the man from the Church by excommunicating him”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Your glorying is not good,.... Their glorying in their outward flourishing condition, in their riches and wealth, and in their ministers, in their wisdom and parts when under such an humbling dispensation; and especially if their glorying was in the sin itself, and their connivance at it, it was far from being good, it was very criminal, as the consequence of it was dangerous: know ye not that a little leaven leaveneth the whole lump? This, in nature, is what everybody knows; and the proverb, which is much used by the Jews (f), was common in the mouths of all, and the meaning of it easy to be understood: thus, whether applied to the leaven of false doctrine, nothing is more manifest, than when this is let alone, and a stop is not put to it, it increases to more ungodliness; or to vice and immorality, as here; which if not taken notice of by a church, is not faithfully reproved and severely censured, as the case requires, will endanger the whole community; it may spread by example, and, under the connivance of the church, to the corrupting of good manners, and infecting of many. (f) Neve Shalom apud Caphtor, fol. 41. 1.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Your glorying is not good - You are triumphing in your superior knowledge, and busily employed in setting up and supporting your respective teachers, while the Church is left under the most scandalous corruptions - corruptions which threaten its very existence if not purged away. Know ye not - With all your boasted wisdom, do you not know and acknowledge the truth of a common maxim, a little leaven leaveneth the whole lump? If this leaven - the incestuous person, be permitted to remain among you; if his conduct be not exposed by the most formidable censure; the flood-gates of impurity will be opened on the Church, and the whole state of Christianity ruined in Corinth.”
Source
1849
A.D.
1774–1849
“Your glorying is not good, when you suffer such a scandal among you: you have little reason to boast of your masters, or even of the gifts and graces you received. A little leaven corrupteth the whole mass; a public scandal, when not punished, is of dangerous consequence. — Purge out the old leaven. He alludes to the precept given to the Jews of having no leaven in their houses during the seven days of the Paschal feast. For our Pasch, i.e. Paschal lamb, Christ is sacrificed: and Christians, says St. Chrysostom, must keep this feast continually, by always abstaining from the leaven of sin. (Witham)”
Source
1863
A.D.
1796–1863
“G. P. "leaveneth the whole lump." The ancient manuscript of Clermont has the Vulgate reading. The apostle speaks of old or bad leaven, to which he compares vice. Gal. v. 9. " If he remain unpunished, and his sin be unavenged, he will corrupt others." St. Chrysostom.”
1871
A.D.
1871
“Your glorying in your own attainments and those of your favorite teachers (Co1 3:21; Co1 4:19; Co1 5:2), while all the while ye connive at such a scandal, is quite unseemly. a little leaven leaveth . . . whole lump-- (Gal 5:9), namely, with present complicity in the guilt, and the danger of future contagion (Co1 15:33; Ti2 2:17).”
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.