How could anybody prove the doctrine of emanation, one way or the other?

A motive behind the development of the doctrine of emanation can be found in the questions:

Al-Farabi's doctrine of emanation became generally accepted by the Faylasufs.

The early church theologians were probably made aware of this concept, and thus of the doctrine of emanation, by the Gnostics.

The poet's mediating role between two worlds - transcendent forms and historical actuality - corresponds to the Neoplatonic doctrine of emanation.

In the early essay De Gravitatione et Aequipondio Fluidorum, he had returned to the old Platonic doctrine of emanation.

However, the neo-Platonic trinity has the doctrine of emanation, or "eternal derivation", a timeless procedure of generation having as a source the One and claimed to be paralleled with the generation of the light from the Sun.

To the doctrine of emanation, based, according to him, upon the Aristotelian cosmological principle that no simple being can produce a compound being, he objects in the form of the following query: "Why did the emanation stop at the lunar sphere?"

In the tenth century, the Ismailis revived this mythology which had been abandoned by Persian Muslims when they converted to Islam but which was still part of their cultural inheritance, and fused it imaginatively with the Platonic doctrine of emanation.

Like the Faylasufs, they adhered to the Platonic doctrine of emanation rather than the traditional Koranic doctrine of creation ex nihilo: the world expressed the divine Reason and man could participate in the divine and return to the One by purifying his rational powers.