How can one be mortal, but eternal?

If there is something I’m quite certain is about my own mortality, meaning by this, my potential lack of eternity. I don’t buy the concept that body and mind are separated and one can float into yonder while the other will decompose. I might be surprised if my assumption were false, but we’ll see!

This said, I believe in what my countryman Antoine Lavoisier once said: “Nothing is lost, nothing is created, everything is transformed" as my cells are certain to be recycled for another purpose after my demise, and whatever I’ve done or created, good or bad, is likely to follow me for a long time if someone doesn’t decide to trash it. 

Did I mention the tiny part of me that created my offspring? 

So, based on these considerations, I can console myself by thinking I’m leaving a trail of eternity in or around me, maybe not as lasting as Mozart or Spinoza’s, but who cares? Mortal body and mind, but eternal legacy...