Really , all things and persons are related to us, but according to our nature, they act on us not at once, but in succession, and we are made aware of their presence one at a time. All persons, all things which we have known, are here present, and many more than we see; the world is full.
From Nominalist and Realist, Essays, Second Series by Ralph Waldo Emerson
After I thought about this, it was fascinating. It seems to be true that people come in out of our lives in succession. I don't know about you, but sometimes people return to my life when I start thinking about them, and disappear when I stop. I've become very careful with my thoughts as a result.
It is hard to do.