A further thought to add to the earlier reflection on universals and particulars:
Ultimate reality — truth — is a Person: “I am the Truth,” Jesus says. Because the Truth is also the divine Word, one expects propositions, and there are propositions. But because the Truth is a Person, one expects more than propositions: one expects acts in history, questions, commands, stories, emotions, all the true things of which a person is capable. And there they are. These lay claim to truth in the same way that propositions do: they are the derivative truth that comes from being a reflection of Truth, the Person.A life that honors God — “walking in the truth,” the apostle John calls it — derives its truth in the same way: by reflecting Christ.
This is another reason why universals and particulars are equally ultimate. When the divine Word is made flesh, when Truth is a person with hair of a certain length and eyes of a certain color, particulars and universals have met and kissed, and can never be separated.
Which leaves us with a burning question: how are universals and particulars related? It’s a question that has plagued philosophers for centuries (again, see Rushdoony’s The One and the Many for details on the history). Christians have an answer to this question: “The same way unity and diversity are related in the Trinity.” We have a word for it: perichoresis, the mutual indwelling of the Persons of the Trinity in one another. So we might say that in the world, universals and particulars are perichoretically related — each indwells the other, as in the Trinity. Which is to say, we don’t understand the phenomenon in the world any better than we understand the Trinitarian phenomenon of which it is a reflection. But since the world is created by the Trinity and reflects the Trinity, we expect to encounter a mystery on this point, and it should not surprise us that the answer is beyond our ken.
Discovering that the thing is, finally and forever, beyond our reach forces us to realize that we are not God, and never will be. There are two possible responses to this: glorify Yahweh in gratitude, or be offended and ungrateful. One of them is life, health and peace, and the other is struggle, sickness and death — the same two choices humanity has always faced, from the Garden right down to today.