Is like unto leaven (omoia estin zumh). In its pervasive power. Curiously enough some people deny that Jesus here likens the expanding power of the Kingdom of heaven to leaven, because, they say, leaven is the symbol of corruption. But the language of Jesus is not to be explained away by such exegetical jugglery. The devil is called like a lion by Peter ( 1 Peter 5:8 ) and Jesus in Revelation is called the Lion of the Tribe of Judah ( Revelation 5:5 ). The leaven permeates all the "wheaten meal" (aleurou) till the whole is leavened. There is nothing in the "three measures," merely a common amount to bake. Dr. T.R. Glover in his Jesus of History suggests that Jesus used to notice his mother using that amount of wheat flour in baking bread. To find the Trinity here is, of course, quite beside the mark. The word for leaven, zumh, is from zew, to boil, to seethe, and so pervasive fermentation.