@WBYeats,
…talking about the tenses in English
Here 'English' refers to the English language.
But 'the English tenses' sounds like you are making a contrast:
…talking about the English tenses, as opposed to those of German and the Nordic languages,…
The Master treated me very well when I was his servant.
-As the professor said, we are required...
The professor told us…
You are referring specifically to the tenses (as opposed to any other aspect of English grammar); to your Master; and a specific professor