Now and Then

[Achebe]

Now and then, I see your face
in a memory, in a picture.
I wonder how it looks today
under the shade of age.
Once in a while,
since i don't think so much about you
anymore,
I believe time has done away
with its beauty;

That your eyes don't shine,
and your lips have thinned,
and your skin sags.

Other times 
I imagine you dignified,
wearing the crown of experience---
gazing neither behind or ahead,
but staring squarely at the moment.
You watch as it passes,
taking with it another 
fine detail of your sunken face...
Another detail,
like all those gone lost 
somewhere in my mind.

I've crossed out the lines that I think hang oddly between the first and second stanzas, belonging to the first and therefore not forming any kind of bridge b/w S1 and S2 despite being in the middle. Also, 'eyes shining' and 'skin sagging' have been done to death (as has "done to death").

IMO ending would read better if the details were supposedly lost to the outside world, but hidden somewhere in the poet's mind. That, in fact, may well have been your intention, but it's not apparent. For instance:

like all those lost and hidden
now somewhere in my mind.