"Let us go back to how you can manipulate time. Think of time as a flowing river." Ziraili said. "One which is extremely strong, and encompasses everything."
"In such a river, with a current nearly impossible to fight, it is mostly considered impossible to fight against the flow."
"That does not mean that time is constant, however. We've already discussed how some things can affect its passing."
Eldrian nodded. "Right. Gravity and velocity."
"Indeed. Time passes fastest when there is no matter present and when there is no gravity. The more gravity there is, the slower it passes. You can think of matter and the gravity its existence causes as banks in a river. Causing the flow to alter and slow. Yet, it does not stop."
"Unless you somehow move at the speed of light, right?"
"Let us ignore that for now, since that isn't quite the same thing. I just want you to understand how you are able to manipulate time."
"Okay?"
I hope this made some sense. :)