Although naturally immaterial, spiritual beings, Tolkien makes the free and hence contingent embodiment of the Valar a necessary condition for the exercise of their sub-creative power and influence in the physical world. More striking still is Tolkien’s representation of this act of voluntary incarnation in terms of spiritual condescension and sacrifice. In the Ainulindalë we read:
Thus it came to pass that of the Ainur some abode still with Ilúvatar beyond the confines of the World; but others, and among them many of the greatest and most fair, took the leave of Ilúvatar and descended into it. But this condition Ilúvatar made, or it is the necessity of their love, that their power should thenceforward be contained and bounded in the World, to be within it for ever, until it is complete, so that they are its life and it is theirs. And therefore they are named the Valar, the Powers of the World. (S 20)
In order to enter the physical world which they love and to help fashion it for the future coming of the Children of Ilúvatar whom they adore, the Valar are required to sacrifice something of themselves by relinquishing the use of some of their natural potency. In order to carry out their sub-creative tasks, in other words, there must first be a certain reduction or focusing of the Valar’s power, making them adequate, adapted, or “proportionate,” as Thomas might say, to the new, material, environment they are to inhabit and govern.