持っていること vs 持っていたこと

Question

When I was writing a composition in Japanese I wrote this sentence:

東京メトロでは、日本人は僕がとても重い鞄を三つ持っていたことに気が付きましたから、荷物を持つのを手伝ってくれました

What I wanted to say is: In the metro, since Japanese people realized I was carrying 3 bags which were very heavy, they helped me to carry the baggage

I got corrected the 持っていた I wrote for 持っている but what I wanted to say is "I was carrying", that is, in the past. Why is it used in Japanese the present tense? Is there a rule or something? I got confused because of that and now I don't know when to use the present or the past in these kind of constructions in Japanese, even when in English we use the past tense.

Answer 1

The problem here is time agreement. I first left a comment because I don't feel very much confident at explaining it.

First, with ていた

AはBがCを持っていたことに気づいた。
A realized that B had been holding C.

Second, with ている

AはBがCを持っていることに気づいた。
A realized that B was holding C.

How so? The depend clause is subordinated to the tense of the main clause. That does mean that if the tense of the main clause is past and the depend clause is "present" then the action expressed by depend clause is at the same time as the main clause. However, if the main and depend clauses end with past tense then the past of the depend clause is older than the one of the main clause.

Answer 2

I don't think your sentence is wrong. You can use the past tense if you want.

I am not sure if it applies to your case or not, but I have found the following.
According to "A Dictionary of Intermediate Japanese Grammar", page 37:

"....tense switching is a strategy available to the writer to differentiate a stage and a set of chronological events that occur within that stage. The stage is certainly important in that it defines a space in which a drama develops, but it is less important than the drama itself.

So important, dramatic information is described in the past tense, whereas relatively unimportant circumstantial information is described in the nonpast tense.

The use of such a nonpast tenses has an effect of creating a vivid sense of immediateness for the reader.
....
A part of a past event (often a state rather than an action) can be described using the nonpast tense, if the writer perceives it to be relatively unimportant circumstantial information that has no direct bearing upon the major story line."