Albert Barnes' Notes on the Whole Bible - Galatians 5:9
A little leaven ... - This is evidently a proverbial expression; see it explained in the notes at 1 Corinthians 5:6. Its meaning here is, that the embracing of the errors which they had adopted was to be traced to some influence existing among themselves, and acting like leaven. It may either mean that there was existing among them from the first a slight tendency to conform to rites and customs, and that this had now like leaven pervaded the mass; or it may mean that the false teachers there... read more
The Pulpit Commentary - Galatians 5:9
Leaven. A familiar proverb applied in the present instance to doctrinal errors, introduced by a small party of Judaizers, but tending to spread through the whole community of Galatian Christians. The proverb is useful, however, as a caution against the spreading of evil generally. I. THE PRINCIPLE . Evil is like leaven. 1. It has a life of its own. Leaven is the yeast-plant. We must not neglect evil with contempt as an inert dead thing. A low and horrible kind of life infests... read more