Never forget posterity when devising a policy. Never think of posterity when making a speech
When something is recorded for posterity then it is written down for future generations to read and learn about. Posterity quotes can be found by many people from the past, and when you browse these you may find some that are inspirational. You may want to save something for posterity because you believe that it is important for future generations to know about the information that is saved. Information that is saved for the future may contain insights into the details of certain events or people that should never be forgotten or overlooked. Victims of war and crime both are often placed in a memorial for posterity, or honored in some other way that ensures that these victims are remembered by generations in the future and are not forgotten over time.