  To illustrate this divergence Henry uses a particularly striking image: possible existences are arranged in a circle around God, so that they are all equidistant, while essences are arranged in a straight line, beginning with the noblest creature (the highest angel) and ending with the lowest form of being (prime matter). Creatural essences are thus arranged as a hierarchical and essentially ordered whole; and this is not a mere tautology, since “essentially ordered” refers to those causal series in which the simultaneous presence of all terms is required for the production of an effect and in which, consequently, a missing link in the chain is enough to invalidate any efficacy with regard to the effects. This means that while the second term depends directly and exclusively on the first, the third depends on the first and the second, the forth on the first three, and so on. A series of this type is clearly neither open nor infinite, since if it were there would no longer be an ordered relation between the terms.