The philosophy of Heracleitus cannot be shown to be borrowed from Zoroaster, and still less the myths of Plato.
The local arrangement of the vision is less distinct than that of the Phaedrus and Phaedo.

Astronomy is mingled with symbolism and mythology; the great sphere of heaven is represented under the symbol of a cylinder or box, containing the seven orbits of the planets and the fixed stars; this is suspended from an axis or spindle which turns on the knees of Necessity; the revolutions of the seven orbits contained in the cylinder are guided by the fates, and their harmonious motion produces the music of the spheres.

Through the innermost or eighth of these, which is the moon, is passed the spindle; but it is doubtful whether this is the continuation of the column of light, from which the pilgrims contemplate the heavens; the words of Plato imply that they are connected, but not the same.

The column itself is clearly not of adamant.

The spindle (which is of adamant) is fastened to the ends of the chains which extend to the middle of the column of light--this column is said to hold together the heaven; but whether it hangs from the spindle, or is at right angles to it, is not explained.