An unopened envelope on the counter grows. Everyone knows this and everyone leaves it there anyway, and by Thursday it is no longer a bill, it is a presence in the kitchen.
Opened, it is a number. Frequently a worse number than you hoped for, and still a finite one, which is a completely different category of thing from a dread with no edges.
Walking towards something does not make it smaller. It makes it specific, and specific is what a person can actually work with.