Why is it important to remember the past?
It is very important to study and remember the past to avoid repeating the mistakes of the past. History is littered with politicians who have not studied the past and have fallen into the same trap as their predecessors. British, French and German Generals dismissed the lessons of the machine gun used in the US Civil War as an American phenomenom, only to discover their own troops being slaughtered by the thousand by this weapon, Politicians today seem to think they are so clever that they can run the country (or the World) without the benefit of the hard won experience of those who went before. The study of history is important also to understand why things are as they are. To understand why Al Qaeda hate the USA, why the IRA hate the British, why the Palestinians hate the Israelis etc. Finally, it is important to remember those who made sacrifices (often their very lives) to ensure our freedoms. Answer We must also not forget the past of our own ancestors in the past. Some have accomplished great deeds and some are famous. Just think, if we didn't have a past what would we be today. Without a past we couldn't go through life without (hopefully) fond memories of a close relationship with either our parents, siblings or friends. We would cease to grow and mature.
Those who have forgotten the errors of the past are destined to repeat them.
Souvenirs are important because you use them to remember places you have been to and things you have seen. eg: You go to London, visit Big Ben - you could buy a mini model of Big Ben, and put it on a shelf, and when you walk past it you would think; " Oh, I remember when I went to London! It was awesome" ect.
What is the difference in meaning between remember to post a letter and remember posting the letter?
As the great philosopher Georges Santayana said, "Those who do not remember the past are condemned to repeat it". In other words, if you understand your past history you can learn from your mistakes and not repeat them in the future. However this also means you can learn from your successes and endeavour in future to use the same techniques where possible to ensure future success.