Page:Theory of Mind of Roger Bacon.djvu/33

 beings that have Will and which are therefore not subject to decay, that is, Intelligences.

Accordingly it is only on the earth that the Species are completed at all; and here only in the case of the four elements, or elemental qualities, and of light. All other action is limited to the production of Species that remain incomplete. But this really is the nature of the Species, that it should remain incomplete, and therefore it is to be expected that in very few cases. Agents should be able to complete their species, that is, actually reproduce themselves.

We are now able to summarize with reference to the limitations of the activity of the Species, and the field of application of the theory. Within the field of the phenomena of qualitative change the theory of the propagation of species is universally valid; in so far as the change is really qualitative, we find no exception where this propagation is not valid. All substances are able to produce Species, and are continually doing so. But in the case of Accidents this is only partly true; all of the proper qualities, but none of the common qualities, are able to do so. Among those things which thus actually produce Species, there is further limitation in the carrying of these to complete Effects. Only light and the four primary elements—or better the quality of light and the four elemental qualities—produce Species which can be really completed.

Let us take it as our task, in this critical examination of our Author’s theory, to see whether he has said what he intended, clear of all ambiguities and contradictions, and whether his theory thus elaborated permits of the applications which he intended. And here it is important that we bear in mind the circumstances of his composition; for, this will enable us to place a fairer estimate upon his theory, truly great though it was, than he himself could do. It is part of a “Persuasio,” a splendid attempt to gain the ear of the Pope for future work; his eye was fixed on the “Scriptum