Ab initio means "from the beginning" and appears in poetry to signal origins, first causes, or foundational moments. Poets invoke this phrase when tracing the genesis of love, conflict, creation, or understanding back to its source. It carries philosophical weight, suggesting that certain truths or conditions were inherent from inception rather than developed over time. In literary contexts, ab initio often frames narratives of cosmogony, personal history, or the evolution of ideas, emphasizing that what follows was inevitable or predestined from the outset. The phrase lends gravitas and classical authority to poetic declarations about essential nature.

Ab initio differs from in medias res, the latter being Homer's technique of beginning in the middle of action. Poets use ab initio when causation matters more than dramatic impact, when they want to trace consequences from their origins. The phrase appears frequently in legal contexts (a contract void ab initio was never valid) and philosophical discussions about first principles. In poetry, it often signals an etiological impulse—the desire to explain how things came to be. Related to ab ovo but less specific; ab initio means "from the beginning" generally, while ab ovo specifically invokes the image of Helen's egg. Useful for poems exploring inheritance, original sin, or the question of whether certain outcomes were inevitable from the start.