330. Common Essence and Individualized Essence. -- On the relation between individual and universal, Scotus teaches that the individual alone possesses full and complete substantiality in nature (secundum naturam); the universal, as an independent form, is a product of thought (secundum intellectum). At the same time, the essence itself, which necessarily assumes individuality in the real world or universality in the sphere of intellectual thought, is something in itself (secundum se); it is ontologically anterior to the twofold determination.^{1} The essentia secundum se, which St. Thomas holds to be only a concept of the individual substance apprehended under a certain aspect, is for Scotus an objective reality, sui generis, having a unity of its own. Not only is the materia primo prima endowed with some special sort of real being, but each and every universal form, generic and specific, in a word, each separate element of essence, capable of entering as constituent into various substances, has its own special being or reality: which thus binds into a peculiar sort of real unity all the subordinate individual things in which that common or class element is found. Cuilibet universali correspondet in re aliquis gradus entitatis in quo conveniunt contenta. How are we to reconcile this teaching with the distinct, substantial individuality of the things of Nature around us? Scotus offers a characteristically subtle explanation: the unity of essence which belongs to every element of essence prior to, and independently of, its "contraction" in the individual thing, is less than individual unity. It implies in fact not only the function of uniting all the individuals in a community of being, but also incapacity to give that complement of actuality which constitutes the complete and independent substance of the individual thing. And to mark this nice shade of discrimination between unity of essence and individual unity, Scotus invented a new distinction which he called the distinctio formalis a parte rei. While the distinctio realis exists between two really different things, and the distinctio rationis multiplies our concepts of one and the same thing, to enable us to consider it from different (d. rationis cum fundamento in re) or identical (d. rationis sine fundamento in re) standpoints, the distinctio formalis a parte rei points, in one and the same individual substance, to the objective forms or formalities that are realized in it, and really in it, independently of any intellectual act of ours. Having once established this distinctio formalis a parte rei, Scotus makes extensive use of it in his metaphysics. It exists between materia primo prima and its various substantial forms, between God and His attributes, between the soul and its faculties, and in general between the metaphysical grades of being. It pervades the whole Scotist system, and has given the latter a name: by his "formalism" Scotus wished at all costs to remain true to scholasticism.

The Principle of Individuation -- that which gives individual identity and distinguishes the individual from all other individuals of the same class -- results, according to Scotus, from the determination conferred on the being by its most perfect form, the form which, in the genesis of things, is the term of their real production. This form puts a definite impress on the specific essence (contrahere speciem); it determines the latter to be this individual and not that or any other, adesse hanc rem. This led Scotus's disciples to say that "haecceitas" is the Principle of Individuation. According to this teaching, spiritual beings and separated human souls are individualized within their respective species.

{1} "Licet enim (natura) nunquam sit realiter sine aliquo istorum, non tamen est de se aliquod istorum, ita etiam in rerum natura secundum illam entitatem habet verum 'esse' extra animam reale: et secundum illam entitatem habet unitatem sibi proportionabilem, quae est indifferens ad singularitatem, its quad non repugnat illi unitati de se, quod cum quacumque unitate singularitatis ponatur" (In L. Sent., 2, dist. iii., q. I, 7, p. 357. Cf. STÖCKL, op. cit., p. 801).