1} Universe has no purpose, except the purpose each human wants to assign to it.
2} 3D tetrahedron divides space into three parts:
.....all that exists internal the tetrahedron,
.....all that exists outside of the tetrahedron,
...all that seperates the internal space from the external space
Paraphrasing Bucky Fuller ideas in the latter three above.
3} Universe has no desire. Only humans, and some other animals have access to desire, to whatever degree.
3 = structural integrity { finite, whole }
4 = Systemic integrity { finite, whole }
Infinite = lack of structural and systemic whole-ness