I haven’t written to him for 3 weeks. = The last time………………………………………………………………
It’s months since we decorated this room
=We haven’t…………………………………………….
I didn’t know how to swim until I was 17 years old.
=Not until

1. I wrote to him was 3 weeks ago.

2. decorated this room for months.

3. Not until I was 17 years old did I know how to swim.

the most likely reason why dante included the names of historical figures in his well-known masterpiece the divine comedy is because he was trying to expose his own historical judgement to the figures. he settles different characters of the occidental culture in parts of the hell, purgatory and paradise constituting a spiritual judgment according to his thought.