Analysis of To Robert Louis Stevenson

I never saw you, never grasped your hand,
Nor wrote nor read lines absence loves to trace,
Ne'er with you sate in your accustomed place,
Nor waited for your coming on sea or land.
But this I know, if along unseen strand,
Or anywhere in God's eternal space,
You heard my voice, or I beheld your face,
That we should greet, and both would understand.
So, till that hour, wherever you abide,
On circling star, or interstellar sea,
Or where, from man's imagination free,
There moves no planet and there sounds no tide,
Welcome, as though from friend long known and tried,
This gift of loving fellowship from me.