He is the very bliss of the infinite, because bliss is the perfect possession of infinite life. Now, it is in the production of the Spirit that the genesis of infinite life terminates and is complete. He is, then, the expression of the perfect possession and enjoyment of the infinite life—the living Blessedness of the infinite. The last law which governs the mystery of God's life, and which is a consequence of all the laws we have explained, is the law of insidence.
This implies the indwelling of all the divine persons in each other. It is founded both on the community of essence and the very nature of personalities.
For the essence of the three divine persons, being one and most simple, it follows that they all meet in it, and consequently dwell in each other. On the other hand, what constitutes them persons is essentially a relation. Now, a relation necessarily asks for and includes the relative term. The intelligent activity is such, because in him dwells the Word, his infinite expression. The Word is such, because he is the expression of the intelligent activity, and dwells in him. The Spirit necessarily dwells in both, because he is the subsisting aspiration of the activity toward its conception, and of the conception toward its principle.
"Believe that the Father is in me, and I in the Father." (St. John.)
With these laws, we conclude the first part of the problem of multiplicity raised by pantheism. It is true, as pantheism affirms, that there must be a certain multiplicity in the unity of infinite essence. For, without a certain multiplicity, no being can exist or be intelligible. Pantheism, in giving such prominent importance to the problem, has rendered great service to philosophy and to religion, and has cut off, in the very bud, all those objections raised by the superficial reason of Arians or anti-trinitarians of old, or Unitarians of modern times. But, as we have seen, however able in raising the problem, Pantheism utterly fails in resolving it; and, in its effort to explain the problem, destroys both the terms to be reconciled. Catholicity, fully conscious of the immense value of the problem, unflinchingly asserts that it alone has the secret of its solution. Without at all assuming to explain away its super-intelligibility, it lays down such an answer as fully satisfies the mind which can appreciate the importance and the sublimity of the problem, and follow it into the depths of its explanation. The infinite, says Catholicity, is not infinite as an abstraction or potentiality, a germ as Pantheism affirms, which ceases to be infinite when it passes into multiplicity; the infinite is actuality itself.
This actuality consists in a first personality unborn and unbegotten, with full consciousness of himself and his infinite perfection. This personality is active intelligence, and in intelligencing his infinite perfection, begets a conception, an intelligible expression of that perfection, a second person. The active intelligence loves his infinite personality conceived by him in his intelligence. This love is a third personality.
Three personalities or terminations of one infinite actuality: a multiplicity in unity; unity without being broken by multiplicity; multiplicity without being destroyed by unity.
Hence the infinite is not a dead, immovable, unintelligible unity, but a living, actual, intelligible unity; because it is unity of nature and a trinity of persons; because the unity falls in the essence, the multiplicity, in the terminations of the essence.