Jewish writers used yeast in a variety of symbolic ways, but Jesus stresses here the factor all had in common: its ultimately pervasive character. One leavens unleavened meal until the finished product is thoroughly leavened. The amount of flour involved here represents roughly fifty pounds, providing enough bread for over one hundred people. A housewife would not normally fix so much meal and could not knead more than this; the unnatural magnitude of the illustration probably suggests that the kingdom far exceeds daily examples to which it may be compared (so Jeremias 1972:147). That she "hid" (NIV mixed obscures this point) the yeast in the dough also exceeds the comparison and reinforces the image of the hiddenness of the kingdom in this age.