A Quote from Portal 1
GLaDOS
While it has been a faithful companion, your Companion Cube cannot accompany you through the rest of the test. If it could talk - and the Enrichment Center takes this opportunity to remind you that it cannot - it would tell you to go on without it, because it would rather die in a fire than become a burden to you.
More quotes from Portal 1
Momentum, a function of mass and velocity, is conserved between portals. In layman's terms, speedy thing goes in, speedy thing comes out.
This is your fault. I'm going to kill you. And all the cake is gone. You don't even care, do you?
Look: we're both stuck in this place. I'll use lasers to inscribe a line down the center of the facility, and one half will be where you live, and I'll live in the other half. We won't have to try to kill each other or even talk if we don't feel like it.
As part of a required Enrichment Center protocol, the previous statement that we would not monitor the test area was a complete fabrication. We will stop enhancing the truth in three... two... zzzt
Due to mandatory scheduled maintenance, the next test is currently unavailable. It has been replaced with a live-fire course designed for military androids. The Enrichment Center apologizes and wishes you the best of luck.