Spacetime "that same unseen power of the world which impels everyone from age 20 to 40, and from 40 to 80, impels objects inside the horizon irresistably towards the singularity."
-Wheeler etc in "the big black book", describing an objects fall into the singularity of a black hole.
He says this because once you are inside the horizon of a black hole, there exist no reference frames that are at rest relative to the singularity, i.e. no possible act of man or god can halt your fall to the end of your world line. It's a pretty intense thing to say if you consider the subtleties of it.
It made me think about something else though: The magnitude of your 4-velocity (velocity through spacetime, a combination of your regular spatial velocity and your inexorable velocity through time) is constant, in all reference frames. In fact, it is equal to the speed of light.
Consider that briefly. You are hurtling unstoppably through spacetime at the speed of light. Intense.
I think this idea makes time dilation a bit more intuitive though. In your rest frame, the one you cannot help but observe the universe from, you have no spatial velocity, so your plunge through spacetime is entirely in the time direction. Aging at the speed of light.
If you observe someone else from a frame in which they appear to be moving, some of their 4-velocity is in the spatial directions, relative to you, so their plunge through time is slower than yours. Not all their 4-velocity is devoted to time. The symmetry of the situation is an interesting, and classic, consideration; namely that from THEIR point of view time is moving more slowly for YOU. Think about it. It will definately mess with your brain.