Ends

what is the meaning of the song bookends by simon and garfunkel?

I know what i think it means but what do you guys think?
“Time it was, and what a time it was, it was/ A time of innocence, a time of confidences/ Long ago, it must be, I have a photograph/ Preserve your memories, they’re all that’s left you.”

i’ve never heard this song, but from looking at the lyrics you have i think he is saying, "those were the days, back when we were young and innocent and proud and confident, invincible. it was so long ago but i have photographs and memories to keep it real, and those memories are how i will be remembered because they tell who i am." he is talking about back in the day when he was young and how precious the memories of his youth are to him because they have made him who he is..