the next door neighbor
will live forever
but not you
Note: It is literally true that we might live next door to someone we never meet or talk to. It is a missed opportunity, the extent of which we will never know.
But the mention of a neighbor who lives forever takes this out of the literal. Matters we are familiar with—spiritual matters for example—might have a close neighboring tradition or school that we learn late about, if ever. That too can be a missed opportunity, or if we knock and walk in, a new and enlightening discovery. Just one door away.