Huh?

Seriously, this is what I like about TOD; it forces me to learn. Thanks for the link to the "enigma of reserve growth." That was a huge help.

For further analogies, see the next comment. The math is pretty straightforward but inverted in the sense of no one thinks in terms of rates. Once you do that, it may help in understanding.

The "enigma" arises because no one ever thought to come up with a workable model.