> 
> SQUIRE TRELAWNEY, Dr. Livesey, and the rest of
>  these gentlemen having asked me to write down the
>  whole particulars about Treasure Island, from the
>  beginning to the end, keeping nothing back but the
>  bearings of the island, and that only because there is still
>  treasure not yet lifted, **I take up my pen in the year of
>  grace 17—** and go back to the time when my father kept the
>  Admiral Benbow inn and the brown old seaman with the
>  sabre cut first took up his lodging under our roof.
> 
> 
> 

Dose it an expression and mean: I write about it that happened in 18th century?
or Dose it mean: in 18th century I started to write about it?

this contexet is from a novel named: treasure Island.