Using of article 'the ' before profession

Question

I am studying English language. I have read a rule that there must be used article 'a/an' before profession. This rule is written, for example, this blog post says, "You'll see that English puts an indefinite article in front of a profession but German doesn’t." But I think that this rule is not working if I mention profession second, third time. For example I think I could say something next:

Our teacher of english language said that we need to use articles. The teacher said talked about differences between two types of articles.

The question is: is it okay to use 'the' in second mention. And second question: may I say article 'a' before teacher in the second sentence from example.

Answer 1

The same blog post you mention says:

The definite article the is used in front of any noun the listener or reader already knows about.

So, when you say:

Our teacher said that we need to use articles.

we now know about the teacher. Therefore:

The teacher talked about differences between two types of articles.

Is the natural way to say it, because the teacher was mentioned in the previous sentence. You wouldn’t use a instead of the, because you are talking about the teacher you already mentioned.

You could word something this way, though:

A teacher said that we need to use articles. That teacher talked about differences between two types of articles.

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By the way, the “rule” you initially cited is trying to say that you don’t use the word teacher without any kind of modifier. In other words, you would NOT say this:

Teacher said that we need to use articles. Teacher talked about differences between two types of articles. (incorrect)

We don’t generally begin sentences with words like teacher, carpenter, doctor, or policewoman. Instead, we use article, possessive pronouns, or some other determiner:

Our teacher said...
A carpenter told me...
My doctor wants...
That policewoman saw...