When you install the operating system on a new computer from a trusted medium like CD-ROM, you are pretty sure of what state the system is in. integrit uses the phrase "known state" for this situation.
When you plug that machine into the internet and go to sleep, the next day when you wake up you don't know what the state of the machine is. The machine's "current state" may or may not be different from the way it was last night. (It was in a known state last night.)