Click on the phrases to see them in context. The original texts by Immanuel Kant and David Hume are available from the Gutenberg Projet.

Thirdly, suppose that every event in the world happens in accordance with the laws of nature; the causality of a cause must itself be an event and necessitates a regress to a still higher cause, and consequently the unceasing prolongation of the series of conditions a parte priorI. Operative nature is therefore too large for every conception we can form in the synthesis of cosmical events.