And their word will eat as a gangrene I have been told by Benedict Textor, a physician, that this passage is badly translated by Erasmus, who, out of two diseases quite different from each other, has made but one disease; for, instead of "gangrene," he has used the word "cancer." Now Galen, in many passages throughout his writings, and especially where he lays down definitions in his small work "On unnatural swellings," distinguishes the one from the other. Paul Aegineta, too, on the authority of Galen, thus in his sixth book defines a "cancer;" that it is "an unequal swelling, with inflated extremities, loathsome to the sight, of a leaden color, and unaccompanied by pain." Next, he enumerates two kinds, as other physicians do; for he says that some "cancers" are concealed and have no ulcer; while others, in which there is a preponderance of the black bile from which they originate, are ulcerous. Of the "gangrene," on the other hand, Galen, both in the small work already quoted, and in his second book to Glauco, Aetius in his fourteenth book, and the same Ægineta in his fourth book, speak to the following effect; that it proceeds from great phlegmons or inflammations, if they fall violently on any member, so that the part which is destitute of heat and vital energy tends to destruction. If that part be quite dead, the Greek writers call the disease sphakelos the Latins sideratio, and the common people call it St. Anthony's fire. I find, indeed, that Cornelius Celsius draws the distinction in this manner, that "cancer "is the genus, and "gangrene" the species; but his mistake is plainly refuted from numerous passages in the works of physicians of high authority. It is possible, also, that he was led astray by the similarity between the Latin words "cancer" and "gangræna." But in the Greek words there can be no mistake of that kind; for karkinos is the name which corresponds to the Latin word "cancer," and denotes both the animal which we call a crab, and the disease; while grammarians think that gangraina is derived apo tou grainein which means "to eat." We must therefore abide by the word "gangrene," which Paul uses, and which best agrees with what he says as to "eating" or "consuming." We have now explained the etymology; but all physicians pronounce the nature of the disease to be such, that, if it be not very speedily counteracted, it spreads to the adjoining parts, and penetrates even to the bones, and does not cease to consume, till it has killed the man. Since, therefore, "gangrene" is immediately followed by (nekrosis) mortification, which rapidly infects the rest of the members till it end in the universal destruction of the body; to this mortal contagion Paul elegantly compares false doctrines; for, if you once give entrance to them, they spread till they have completed the destruction of the Church. The contagion being so destructive, we must meet it early, and not wait till it has gathered strength by progress; for there will then be no time for rendering assistance. The dreadful extinction of the gospel among the Papists arose from this cause, that, through the ignorance or slothfulness of the pastors, corruptions prevailed long and without control, in consequence of which the purity of doctrine was gradually destroyed. Of the number of whom are Hymenaeus and Philetus He points out with the finger the plagues themselves, that all may be on their guard against them; for, if those persons who aim at the ruin of the whole Church are permitted by us to remain concealed, then to some extent we give them power to do injury. It is true that we ought to conceal the faults of brethren, but only those faults the contagion of which is not widely spread. But where there is danger to many, our dissimulation is cruel, if we do not expose in proper time the hidden evil. And why? Is it proper, for the sake of sparing one individual, that a hundred or a thousand persons shall perish through my silence? Besides, Paul did not intend to convey this information to Timothy alone, but he intended to proclaim to all ages and to all nations the wickedness of the two men, in order to shut the door against their base and ruinous doctrine.

And their word - The word, or the discourses of those who love vain and idle disputations.
Will eat as doth a canker - Margin, "gangrene." This word - γάγγραινα gangraina - occurs nowhere else in the New Testament. It is derived from γραιω graiō, γραινω grainō, to devour, corrode," and means "gangrene" or "mortification" - the death of a part, spreading, unless arrested, by degrees over the whole body. The words rendered "will eat," mean "will have nutriment;" that is, will spread over and consume the healthful parts. It will not merely destroy the parts immediately affected, but will extend into the surrounding healthy parts and destroy them also. So it is with erroneous doctrines. They will not merely eat out the truth in the particular matter to which they refer, but they will also spread over and corrupt other truths. The doctrines of religion are closely connected, and are dependent on each other - like the different parts of the human body. One cannot be corrupted without affecting those adjacent to it, and unless checked, the corruption will soon spread over the whole.
Of whom is Hymenaeus and Philetus - In regard to Hymenaeus, see the notes at 1-Timothy 1:20. Of Philetus nothing more is known. They have gained an undesirable immortality, destined to be known to the end of time only as the advocates of error.

Their word will eat as doth a canker - Ὡς γαγγραινα· As a gangrene; i.e. as a mortification in the flesh, where the circulation is entirely stopped, and putrefaction takes place, which continues to corrupt all the circumjacent flesh, spreading more and more till death takes place, unless stopped by a timely and judicious application of medicine. Such is the influence of false doctrine; it fixes its mortal seed in the soul, which continues to corrupt and assimilate every thing to itself, till, if not prevented by a timely application of the word of life, under the direction of the heavenly Physician, it terminates in the bitter pains of an eternal death. To such a gangrene the apostle compares the corrupt doctrines of Hymeneus and Philetus.

And their word will eat as doth a cancer,.... Or "gangrene", which gnaws and feeds upon the flesh, inflames and mortifies as it goes, and spreads swiftly, and endangers the whole body; and is therefore to be speedily taken notice of, and stopped. It is better rendered "gangrene", as in the marginal reading, than "cancer".
"The word "gangrene" is Greek (g), and is derived by some authors from the Paphlagonian "gangra", a goat; it being the character of a goat to browse the grass all around without shifting. It is more correct, perhaps, to derive it from the Greek word "manduco", "consumo", I eat, I consume. The "gangrene" is a disease in the flesh of the part which it corrupts, consumes, and turns black, spreading and seizing itself of the adjoining parts, and is rarely cured without amputation. By the microscope, a gangrene has been discovered to contain an infinite number of little worms engendered in the morbid flesh; and which continually producing new broods, they swarm, and overrun the adjacent parts: if the gangrene proceed to an utter sphacelation (or mortification), and be seated in any of the limbs, or extreme parts, recourse must be had to the operation of amputation''
And so the errors and heresies of false teachers worm and spread, and feed upon the souls of men, and eat up the vitals of religion, or what seemed to be such, and even destroy the very form of godliness; and bring destruction and death, wherever they come; and when they get into Christian churches, threaten the ruin of them; and therefore are to be opposed in time, and those infected with them to be cut off.
Of whom is Hymenaeus and Philetus; these were some of the principal among the false teachers, the chief authors and spreaders of error and heresy: the former of these is mentioned before in 1-Timothy 1:20 along with Alexander, as guilty of blasphemy, and as delivered up to Satan for it. Philetus is a Greek name as well as the other, though it is sometimes found in Roman inscriptions (h): it is very likely that these were both in Asia, and probably in Ephesus, or near to it, since the apostle mentions them by name to Timothy, that he might beware of them.
(g) See Chambers's Cyclopedia in the word "Gangrene". (h) Vid. Kirchman. de Funer. Roman. l. 3. c. 10. p. 390.

will eat--literally, "will have pasture." The consuming progress of mortification is the image. They pretend to give rich spiritual pasture to their disciples: the only pasture is that of a spiritual cancer feeding on their vitals.
canker--a "cancer" or "gangrene."
Hymenaeus--(See on 1-Timothy 1:20). After his excommunication he seems to have been readmitted into the Church and again to have troubled it.

And their word - If they go on, will be mischievous as well as vain, and will eat as a gangrene.