E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A little leaven leaveneth the whole lump. Some casual influence has dropped good seed, which has taken root and beareth fruit to perfection. The words are the title of a dramatic poem by Robert Browning. Pippa is a chaste-minded, light-hearted peasant maiden, who resolves to enjoy New Years Day, her only holiday. Various groups of persons overhear her as she passes-by singing her innocent ditties, and some of her stray words, falling into their hearts, act with secret but sure influence for good. (1842.)