Killeen, PR, Fetterman, JG & Bizo, LA 1997, 'Time's causes' in CM Bradshaw & E Szabadi (eds), Time and behaviour: psychological and neurobehavioural analyses, Advances in Psychology Amsterdam, Elsevier, New York, pp. 79-132.
What is time? St. Augustine knew: “I know what time is”, he said, “but if someone asks me, I cannot tell him” (Landes, 1983, p. 1). Not much help. It is the business of scientists to tell, and another ancient philosopher tells us how to tell: Aristotle sought to understand phenomena—and communicate that knowledge— by identifying their four "[be]causes", which he called material, final, efficient, and formal. We have interpreted these as questions about what (description/definition and substrate), why (function), how (mechanism), and like (analogs and models). These four causes organize our analysis of time and timing.