Time appears as one of these concepts impossible to define, nor to perceive as such. Augustine writes, “What then is time? If no one asks me, I know; if I want to explain it to a questioner, I do not know”. Indeed, though impossible to deny its existence, since it seems to be part of the necessary framework (with space) in which we can perceive at all, time cannot be accurately described. None of our 5 senses perceives it: we don’t see, hear, touch time. Even if time is intimately experienced, impossible to get out of, and an essential dimension of our experience and existence, it still is extremely difficult to think about it, grasp it - and certainly, to control it. How do we experience time passing? What is the past, the present and the future, and how does our conception of them shape the way we behave and think? The irreversibility, the ephemerality of time is at the core of our existence - as is our mortality, our very finitude.