The course of things and their connexion is only thinkable by the assumption of a plurality of existences, the reality of which (as distinguished from our knowledge of them) can be conceived only as a multitude of relations.
The only veritable and real unity in the world of existences is the individual; to assert that the universal exists separately ex parte rei would be to reduce individuals to mere accidents of one indivisible form.
Finally, by abstraction from the individual things of sense, the mind is able to contemplate the universal apart from its accompaniments (animal sine homine, asino, et aliis speciebus); these subjective existences are the universalia post rem of the Nominalists and Conceptualists.
And in a similar spirit he explains the universalia ante rem as being, not substantial existences in God, but simply God's knowledge of things - a knowledge which is not of universals but of singulars, since these alone exist realiter.
This climax was reached at the very moment when Darwin was publishing the Origin of Species (1859), by which universal opinion has been brought to the position that species, as well as genera, orders and classes, are the subjective expressions of a vast ramifying pedigree in which the only objective existences are individuals, the apparent species as well as higher groups being marked out, not by any distributive law, but by the interaction of living matter and its physical environment, causing the persistence of some forms and the destruction of vast series of ancestral intermediate kinds.
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