But Pensive, I think past objects and subjects remain existent in the past, once it's past.
Past objects and subjects are whatever really isn't the question. The question is of the past itself, whatever that means. In the first case we're applying temporal states as predicates to other things, but in the latter we're talking about the condition and nature of temporality.
The past is nothing but an amalgam of memories of the collective human consciousness. The past itself, as an object, exists not, but the concept of it certainly exists, in the present
. The past
in some sort of extremely weird manner, simmilar to Nothingness
as some sort of regulatory or enabling function or condition of other things (other things like the present) but I am not convinced.