Fresh Fossils

When I went walking on the beach,
 I came to understand.
 With each step I left a footprint;
 A fresh fossil in the sand.
 Looking over my left shoulder,
 Behind lay my own track.
 And I would be my own man Friday,
 or whenever I came back.
 Up ahead I saw the future,
 a stretch of barron beach.
 I knew that I was headed nowhere,
 the horizon out of reach.
 So I turned and headed back,
 I was present in my past.
 Now and then mere twin directions,
 the next intersecting the last.
 There was proof that I had been there,
 and proof I've come and gone.
 Imprinted in the sands of time,
 so why should I walk on?
 Now and then identical,
 though they are not the same.
 And future waves will erase both,
 as if I'd never came.