While studying the past we also learn the source of time formation. The immediate source of its formation was everyday based on the perspective sensitive perception of a constant change of events. But the main condition of time cognition was the moment of a practical action of a person or his speech communication with other people. A practical calculation of time was already very important for people in the past centuries. For example, irrigation works in the Ancient Egypt demanded to take into account the time of flood of rivers, etc.
Present time is a tangible reality, and a person lives only in the present.
We can illustrate the peculiarity of present time taking human life as an example. It presses on him with real troubles and problems. Besides, the most important, existence problems take place in the person's life at present time. Here we mean such problems as life itself, its sense, freedom, happiness, and non-existence as a notion where the life loses its sense. For example, if a nuclear war breaks out the whole mankind will die and there will be no one to solve global problems and there will be no sense for it.