Do information in the past need to be written using present tense?

Question

Currently I'm learning about Changing Time Clauses to Modifying Adverbial Phrases.

Here's an example I picked from my book:

After I heard Marika describe how cold it gets in Minnesota in the winter, I decided not to go there for my vacation in January.

My attempt to change the adverb clause to modifying adverbial phrase:

After hearing Marika describe how cold it gets in Minnesota in the winter, I decided not to go there for my vacation in January.

Now, come to my question. I can agree if "how cold it gets in Minnesota..." is written in a simple present since it's information and we know we would use present tense to describe a fact/information. But, why the word "describe" isn't in past tense? The word "describe" is action in the past, I believe.

I mean, something like: "After hearing Marika described how cold......"

I'd also like to know when we would prefer to use present tense in a past sentence even if the action is in the past.

Maybe, i have feeling that "Marika describe...." is also information. So, it's information that has been told by someone and the other one also told this information. And another question comes, why wouldn't it be "describes" instead of describe?

And what about this:

A) I saw Brian tell something to Jessy yesterday.

B) I saw Brian told something to Jessy yesterday.

Answer 1

There are two issues here.

One: When you say "it's information", I'm not sure if you understand the rule. "It was cold yesterday" is information but it must be given in past tense because it refers to the temperature at a specific time -- yesterday.

Statements that are always true or that will be true indefinitely are stated in the present tense. Like "Pi is the ratio of the circumference of a circle to its diameter" is true today, it was true 1000 years ago, and it will be true 1000 years from now. So we state that in an "eternal present". "Winters in Minnesota are cold" is not really an "eternal truth". Who knows what the climate will be like in Minnesota 5000 years from now, or if Minnesota or anything that could be called "Minnesota" will still exist. But the statement has been true for a long time and will likely be true for a long time to come, so we still use the eternal present.

Two: When the object of a verb is a phrase including another verb, that phrase is usually given in present tense. (I'm sure there's a name for this but I don't know what it is off the top of my head.) Like we say, "Yesterday I saw Jim fall down the stairs." "Saw" is past tense because it happened yesterday, that is, in the past. But "fall" is present tense. I suppose you could say that at the time I saw it, it was happening in the present -- my present.

Note this isn't an eternal present. We use the present even if we're describing a specific event. Presumably Jim doesn't fall down the stairs every day (I hope not, anyway), but we still use the present.