Just like a river that never have the same exact water particle every second, although a person have a same name and seems to look the same he/she is not every the same.
we taken for granted that everyone body and mind change everysingle second. in every second our cell die and renew, we experience learning from our enviroment and our own thought.
If we could accept that a person always experience change and they have a reason of behaving or thinking.
We will be able to accept when someone else change for a better and wont sabotage other changes by mocking others who change for the better.
we will not say this is who i am and i wont be able to change who i am. The fact that you are not drinking milk from milk bottle like when you are baby, not having the same cell from the last year will remove our belief that no one can change.
Finally, if we know we will not ever meet the same person every again. Will we enjoy and treasure our time with that person? will we see that person as the most important person at that moment? or we will play with our phone and angry for a small matter.