Being in Act and Being in Potency

The most fundamental modality of being in act and being in potency is concerned not with movements or operations, but with the very substances of things as such. Each physical reality we encounter comes to be and can cease to be. We ourselves are capable of existing or not existing. There was a time that we did not exist, and there is a time in the future when we will not exist - at least not in the form we do now.