The "Ship of Theseus" is a thought experiment which raises the question of whether a ship who has been on a journey and got its pieces replaced, one by one, is still the same ship at the end of the journey. Although originally posed as a philosophical dilemma, it beautifully illustrates how we perceive life and change.
If I am on a journey - call it life, our most important (and perhaps only) journey through space and time - and got my cells replaced one by one or my organs and bones morphed into larger ones, am I still the same person after some amount of time?
Posed this way, it seems obvious that "The Ship of Theseus" can be in the analyzed in a new light - that of a person growing and changing, both physically and psychologically, throughout her life. If Mary takes a picture of herself each second, from birth to death and analyzes them with care, she would probably not notice any difference. To make this less boring, let's take a picture of her personality too (whatever the meaning of it is). Every photo after 1 second has passed looks almost exactly the same to her when compared to the second before. By applying this reasoning to all photos, without ever looking back to photos from seconds past, she would get to the end and notice no different at all - did she never change with time? She knows (and we know) that she must be wrong; when she looks at the photos from birth, its unmistakable that a huge change has occured, both in her physical attributes and in her way of being - all that makes her Her.
Has she done something wrong in her analysis? One could argue that because we are not perceptive enough, we cannot notice the changes that happened during that second. But the fact is, we never could have - if we take this reasoning to the extreme, every electron that moves inside each atom that constitutes each cell that composes Amy will give rise to a change which we could never notice due to quantum nature of matter. We would never be able to see the effect that each electron in an atom produces - only, after some time, the effect of what many, many atoms gave birth to.
So more than being stuck with imperfection, (which, of course, we already knew), it seems inevitable. It appears that if we are constantly looking at ourselves, both physically and mentally, change never happens.
My answer for this apparent dilemma - the ship of theseus or the ship of life - is that in each second Mary looks at herself, she redefines itself in that moment. What we called "Mary" one second before is now updated to "Mary" one second after. Every time a piece of the boat is replaced, we update our concept of "this ship" - even if the change is not noticeable. So the ship is the same in the eyes of a sailor aboard the ship, but not necessarily the same for someone who only got the see the ship leave and then arrive at a later moment.
This is why change is so difficult, or almost impossible, if we are always looking ourselves in the mirror to see our body and personality - it seems that we have not changed at all; that we failed in growing, in evolving, in getting better. On the other extreme, someone who never looks back can never appreciate the beauty of our own perception; can never contemplate how much she sailed through the tides of time.
Every now and then, it's a good thing to look back and dive into the pool of memories of what we were; to look at the night sky and watch the light of a dying star which we know does not exist anymore.