Cervantes was 58 when Don Quixote was published.
40 would have been considered a ripe old age.
In 1900 ripe old age was 47.
I remember when I was a kid in Oklahoma in the 50s and 60s a neighbor was 30 and PG for the first time! She was considered too old and she was so grumpy! LOL Now a lot of people wait till 30 to have a baby! I was 30 when I had our first child!