The Buddha spoke of impermanence, that nothing lasts, and that failing to understand the real nature of impermanence means suffering. Most of us would agree that impermanence, or change, is a fact of life. If I ask if the weather, a river, or a mountain will always be the same, most will say no. If I ask if we as individuals will never change, again most will say no.
But here is the rub. Our sensitivity to impermanence shows up in our attachments to wishing for the world to be other than it is, unchanging. We exist in a conflicted state where intellectually we understand that everything changes, and all things good or bad pass away, but emotionally we hold onto the things we like and push away the things we do not like. This creates suffering as we are buffeted back and forth by the winds of change, experiencing emotional turmoil as we try mightily to hold onto this and get rid of that, all to no avail.