He and his brother are like plum-trees that grow crooked over standing-pools; they are rich and o'erladen with fruit, but none but crows, pies, and caterpillars feed on them.”The Duchess of Malfi (Kindle Locations 40-41). Kindle Edition.
-- Bosola (Act 1 paragraph Kindle Locations 40-41)

Importance: In the beginning of the play, Antonio asks Bosola about the Duchess’s brothers. Bosola responds by comparing the brothers to twisted fruit-bearing trees, but they are by stagnant water and only pesty birds and insects desire to eat the fruit. The “standing pools” are like sluggish water that just sits around, does not flow, and enables mosquitoes to breed.

Nobly, my lord: as out of the Grecian horse issued many famous princes, so out of brave horsemanship arise the first sparks of growing resolution, that raise the mind to noble action.”The Duchess of Malfi (Kindle Locations 76-77). Kindle Edition.
-- Antonio (Act 1 paragraph Kindle Locations 76-77)

Importance: Ferdinand just told Antonio that Antonio is a good horseman and...