Lyric discussion by bolosky 

Cover art for The Sage lyrics by Emerson, Lake & Palmer

I'm pretty sure that the last line is "our reasons are lost in our rhymes." Listen to the version on "In the Hot Seat" and it's much more clear than the one on Pictures at an Exhibition. Greg Lake's voice seems to have gotten much deeper in the 22 years between them, too.

The song seems to be analogizing life to a journey that alters the traveller. At the end of the journey (old age), the singer is asking someone to be his partner.

I really like the imagery in "Eroded by time's rivers...to the shapes we now posess" for what aging does to a body.

@bolosky I agree that Greg Lake is singing “rhymes”. I think he’s making a play on the old adage “no rhyme nor reason”. In any case, it’s a beautiful song with beautiful and vivid imagery.