There must be more mass in the universe than meets the eye, otherwise the galaxies themselves would fly apart. Like riders on a fast-spinning carousel, the stars whirling around a galaxy are flung outward by their own inertia. Indeed, in the outer reaches of a spiral galaxy like the Milky Way, the stars travel so fast that the gravity from all the other visible matter in the galaxy can not hold them. So some other type of matter, invisible and elusive, must provide the missing mass and the extra gravity.
being confronted with the knowledge that everything you can imagine
is incapable of supporting what you think of as reality, even for
a millisecond is enough to inspire a special kind of fear,
one reserved for: a. domesticated animals and b. domesticated
humans, a fear that comes from the backbreaking limitations enforced
by the subscription to a rationally defined world and the realization
that those limits make you, and your world, worth nothing.