Or else, by the leaven our Lord means the Holy Spirit, the Sower proceeding (as it were) from the seed, which is the word of God. But the three measures of meal, signify the knowledge of the Father, and the Son, and the Holy Spirit, which the woman, that is, Divine wisdom, and the Holy Spirit, impart.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).