WHY is it this way and not the other way around!!!!!

[The Mighty Gorgon]

The retrospective way for calculating reserve at t is:

acc value of premiums - cost of insurance (or acc value of Ax)

But isnt it the other way around?

like loss at issue = Gain of insured - Premium payed as an annuity

and retrospective way is just looking at that at a different time, so why not:

acc value of insurance - acc value of premiums?

Why is it the other way? The manual doesnt explain.

Thanks.
Grrr.