Final answer:
The myth of Er connects the shaft of light that maintains the universe's cohesion to the spindle of Necessity.
Step-by-step explanation:
According to the myth of Er, which is part of Plato's dialogue in The Republic, the shaft of light that holds the universe together is connected to the spindle of Necessity (Ananke). In this allegory, the cosmos is depicted as having the structure of a spindle, with the shaft of light serving as the axis around which the celestial bodies revolve. The spindle, held by Necessity, represents the ultimate form of structure and order in the universe. This myth is part of a larger set of Greek myths that explain natural phenomena and moral concepts using the actions and characteristics of gods, heroes, and cosmic entities.