Two lives that once part, are as ships that divide
When, moment on moment there rushes between
The one and the other, a sea,—
Ah, never can fall from the days that have been
A gleam on the years that shall be.
Notes from Wikiquote
Compare "Ships that pass in the night", Henry Wadsworth Longfellow, Tales of a Wayside Inn (1863), Part III, "The Theologian's Tale: Elizabeth", IV.