Vertical causality locates a dharma within the web of interrelations connecting it with the rise and fall of other dharmas.

The Sarvāstivāda-Vaibhāṣika distinction between a dharma’s activity and capability implies that each dharma or consciousness moment effects the next moment within its series, but it can also act as a contributory condition towards producing a different sort of effect. Activity engenders the next moment within a dharma’s series, while capability generates a different effect and explains the causal efficacy of past dharmas. Williams (1981, 246–247) helpfully notes that we may render this “horizont