You are right - every change, no matter how small, means it's adifferent world to what it was, and is different to what it will be even if the apparent sameness is subtly changing beyond our perception of the miniscule movements bringing about such change, but if such minor changes are imperceptable, then they will only be apparent once a state of critical mass has been achieved to provide the more apparent changes which we can easily detect, and then by reverse logic, conclude that the shades of our reality have lightened or darkened without us ever realising it ..... or something like that.