What is time? Who can explain this easily and briefly? Who can comprehend this even in thought so as to articulate the answer in words? Yet what do we speak of, in our familiar everyday conversation, more than of time? We surely know what we mean when we speak of it. We also know what is meant when we hear someone else talking about it. What then is time? Provided that no one asks me, I know. If I want to explain it to an inquirer, I do not know. But I confidently affirm myself to know that if nothing passes away, there is no past time, and if nothing arrives, there is no future time, and if nothing existed there would be no present time. Take the two tenses, past and future. How can they 'be' when the past is not now present and the future is not yet present? Yet if the present were always present, it would not pass into the past: it would not be time but eternity. If then, in order to be time at all, the present is so made that it passes into the past, how can we say that this present also 'is'? The cause of its being is that it will cease to be. So indeed we cannot truly say that time exists except in the sense that it tends toward non-existence.