Santayana reprised

In general, the more remote a thing seems in time, the less its reality, and w
ith this goes naturally the assumption of its relatively sharp separation from
anything concerning our personal lives.

can you explain it for me, thanks!

People (mistakenly) tend to believe that events which happened a long long time ago cannot have any significant relevance to them personally, simply because they happened so long ago.

The statement coincidentally ties into a recent thread here dealing with Santayana's assertion that "those who cannot remember the past are condemned to repeat it."