They possess the principle of individuation in themselves, he teaches, but plurality of individuals is in such a case equivalent to plurality of species (in eis tot sunt species quot sunt individua).
One of the first of these was the Reprehensorium seu correctorium fratris Thomae, published in 1285 by William Lamarre, in which the Averroistic consequences of the Thomist doctrine of individuation are already pressed home.
It is false, therefore, to speak of matter as the principle of individuation; and if this is so there is no longer any foundation for the Thomist view that in angelic natures every individual constitutes a species apart.
This concentration and obliteration of somites, often accompanied by dislocation of important segmental structures (such as appendages and nerveganglia), may lead to highly developed specialization (individuation, H.
Albert and Aquinas agree in declaring that the principle of individuation is to be found in matter, not, however, in matter as a formless substrate but in determinate matter (materia signata), which is explained to mean matter quantitatively determined in certain respects.