Einstein proposed that time is the fourth dimension. I can perceive the 3 dimensions world that we live in, but it is difficult for me to imagine a fourth dimension. That maybe because it is not something that I can visualise. We tend to only believe what we can see.
But unlike the other 3 dimensions, time cannot be manipulated nor charted. Or can it? Throughout human history we have been trying to manipulate and measure this element.
What is time then? Time is considered a kind of linear progression measured by the clock and the calendar. That it is unchangable and constantly moving. With no regards to anything else. It will not slow down when we are sad (though we might feel it it does) nor speed up when we are happy. It keeps moving from past to future. George Orwell once said "He who controls the present, controls the past. He who controls the past, controls the future."
Is there such thing as present then? Isn't it true that whatever just happened is already in the past and whatever is about to happen is still in the future? Is present the nanosecond THIS particular nanosecond? By wearing a watch and asking "what time is it?" do we therefore possess the present? There is no such thing as present. It is like trying to make and incision right where the past meets the future.
How about the past and the future? The past is something that has gone and the only way we know that it existed is through our memory. But our memory are prone to subjective influence. Did you ever realise that some of your old memory seems to be sweeter than the actual event? Then is the event real since it differs from the memory we have of it? Or the memory a lie since it doesn't coincide with the real event? How can we trust history? It is said that "history" is written by the winner. So there is no such thing as "real" history and therefore, no such thing as "real" past, either.
On the other hand, future is not even here yet. It is nothing but a hypothetical concept. How do you know there is such a thing before it actually happen? For example, we may have plan to do something in the future, say tomorrow. But what if we die before tomorrow. Doesn't that make tomorrow nothing but another illusion?
Then is the concept of "past, present and future" is nothing but an illusion that we created to lie to ourselves that we actually can possess time? This is what we want to do, right? To possess time. We run around all our lives, chasing time, complaining that we don't have enough time, etc.
Have we ever thought that time could be viewed in other way? That time could be a cyclical concept. The Indian mythology believes in the beginning point of time is also the ending point. In another word, there is no beginning nor end of time. This view is also echoed by Buddhism and other oriental philosophies. It is evident everywhere. For example, everyday begins as the sun rises and ends as the sun sets; even yearly seasons move in cycle: spring, summer, autumn, winter... spring.
What does that mean to us if we do see time as cyclical rather than linear? Would we then not put so much importance on lost time? Would we then learn to appreciate each moment more? or less?
There is no such thing as "time". It is nothing but an idea for us to try to understand and to grasp the meaning of changes. Be it linear or cyclical, all we ever have is THIS moment of conciousness.