Space and Motion are complementary forms of the same thing.
Space as Emptyness is that which cannot be measured by the thinking mind; it is the All~Presence that is always available; it expresses itself as welcoming. Its expression is space; its expressing is motion.
The key to the understanding that space and motion are complementary forms of the same thing is to understand relationship. And the clearest way to understand relationship is to understand a couple that appears as separate individuals that are not separate in truth.
In this light ‘what is’ is relationship that is not limited to any definition of relating or relations. it is simultaneously definite and infinite, ephemeral and perpetual.