[Grammar] "of his day" or "of his days"?

[thincat]

Hi,

In the following sentence, which phrase should I use? "of his day" or "of his days"?

"He is one of the most eminent linguistic authorities____."

Do these 2 phrases differ in meaning?

Thank you!

 

[emsr2d2]

"Of his day" suggests a past situation. We don't say "of his days".

Shakespeare was one of the most prolific playwrights of his day.