The lines of communication in this particular Tree of Life are based on the cubic alignments of the Zodiac, as seen on the right, with the planetary path arrangements relating to their perspective planetary spheres.
Six is the Perfect Product of the Triune nature of Zero (>0<) and thereby manifests into a perfect physical form called a Cube of Space; a six equally sided three-dimensional block.
Mankind, unlike any other lifeform, has certainly considered the concept and construction of a container very thoroughly and effectively. Humans are masters of making a box go further than any other animal; from the simple jewelry box, to cars, ships, planes, and even spaceships, sending them to the outer reaches of our solar system and beyond.