Quaternion (poetry)

Quaternion is a poetry style in which the theme is divided into four parts.
Characteristics.
Each part of a quaternion explores the complementary natures of the theme or subject. The word "quaternion" is derived from the Latin word "quaterni", meaning "four by four". The poem may be in any poetic form and 'offers poets the chance to experiment with varied rhetorical structures'.
Examples.
Anne Bradstreet, America's first significant poet, wrote four quaternions: