The ultimate abstract principle of actual existence for Whitehead is creativity. Actual existence is a process of becoming, and "... 'becoming' is a creative advance into novelty." It is manifest in what can be called 'singular causality'. This term may be contrasted with 'nomic causality'. An example of singular causation is that I woke this morning because my alarm clock rang. An example of nomic causation is that alarm clocks generally wake people in the morning. Aristotle recognises singular causality as efficient causality. For Whitehead, there are many contributory singular causes for an event. A further contributory singular cause of my being awoken by my alarm clock this morning was that I was lying asleep near it till it rang.