Change
Nothing will ever stay the same. Change is a certainty.
I might be similar to the 12 year old me, but I am not the same. I'm not the same as the last week me, and it is unfair to judge me according to her.
I will never feel the same. A similar feeling is a possibility, but it is not the same.
Not a single second that passes is the same as the one before.
Familiarity is similarity; it is never a lack of change.
Change is the only constant value. And in that, it is never constant.