Trinitarian theology is a difficult subject. Scriptural references are few and their meaning is not obvious - indeed, they can easily be read as contradictory. In fact, there is no explicit description of the Trinity in the scriptures at all - the orthodox view of the Trinity (three persons in one God) is an inferential conclusion from scripture that took generations to piece together. Having arrived at that conclusion, the next problem was to understand exactly what it meant - a problem difficult enough that many argued that it was simply a mystery the answer to which we might know in the next life but not this.

This famously difficult problem is the subject of Augustine's "The Trinity". In addressing it, he has two motives. His first motive is to combat non-Trinitarian heresy by showing the scriptural support for the concept and by showing that it is not inherently contradictory. His second motive is to attempt to understand the Trinity more deeply, to satisfy the scriptural directive to "seek His face evermore".

"The Trinity" is a long book, the second longest work in the Augustinian corpus, and one that he worked on, intermittently, for sixteen years. He might not have finished it had not the unauthorized publication of the first twelve "books", led him to write the final three in order to avoid having the work available only in an incomplete form.

"The Trinity" begins with a consideration of the Scriptural references to the Trinity, with the aim of reconciling them and explaining them through the supposition of three equal persons in one God. Augustine is at particular pains to maintain the equality of the persons: that the Son is equal to the Father, and the Holy Spirit equal to both. Of particular concern to Augustine are the references to the Son and Holy Spirit being sent, with the implication that the Father who sends must be superior to them. This presentation takes up the first eight books.

From there Augustine aims to develop some deeper understanding of the nature of the Trinity. His approach is to use the fact that the Man was created in the image of God. Given this, Augustine reasons, there should be some image of the Trinity in man. This leads to the consideration of a succession of trinities - the lover, beloved, and love; memory, understanding, and will; the objects of sense, the will to attend to them, and the sense impressions of them; etc. This presentation, which take up the next four books, is interesting, but often perplexing. It is easy for the reader to see that the trinities he names are not analogues of the divine Trinity, and it can be perplexing to attempt to understand how Augustine intends to bring this discussion of the trinities in man together.

It is in the last few books, written after the premature publication of the earlier books, that Augustine works to reverse the centrifugal tendencies of his discussion of the trinities in man and unify them into a whole. The trinities in man are held up not as exact analogues to that in God, but as a ladder, starting with the most carnal and rising towards the most spiritual; we do not find a single Trinity like that of God within ourselves, but we do find a series of them that we can ascend, and in ascending it we approach the divine Trinity and a deeper understanding of God.

There is much discussion in contemporary theology about the Trinity (e.g. Moltmann, LaCugna, Gunton, Pannenberg, Rahner, Barth). In order to appreciate the discussion intelligently, you ought to go back to the source of the Western model of the Trinity. One of Augustine's analogies for the Trinity is the Father the Lover, the Son the Beloved, and the Spirit as the Love. Quite a few theologians are critical of Augustine's emphasis on the unity of the Triune God (e.g. Moltmann, Pannenberg, LaCugna). It is worth reading this work just to put their work in perspective.

This work is more than just an exposition of theology. Augustine has a long discussion of perception (memory, understanding and will), because he needs to give an account for how human seeing can fulfill its supernatural vocation to see God. Some of his discussion anticipates some of the concerns of the Enlightenment. E.g. if the representation I recall in my mind is from my memory, but is also shaped by my will, how do I know I have an accurate representation of reality?

Another reason to get this work is that any attempt to tackle the Trinity ends up by a mini-systematics. In a fairly short space, a close read of the work will pay a mountain of dividends.

In particular, Edmund Hill did an invaluable job editing and translating the work. The introductory notes, the endnotes, and the essays scattered throughout the work are worth the price of the book itself. I have gotten a lot more out of the work because of Hill's commentary (and they are not overly intrusive). Some of Hill's translations are a little bit too colloquial for my taste, but he wanted to write a dynamic translation. If you want a literal translation of this work, you can like in other places.

All in all, this is one of the all-time classics in Christian theology.

Nobody doubts the role that Frege played with philosophy of logic, math and language. However, so little is known about Husserl's role on it. Claire Ortiz Hill exposes the fact that Husserl was influenced by the mathematicians of his time. Husserl was the student and assistant of the great mathematician Karl Weiestrass, for 15 years he was the colleague and close friend of Georg Cantor, the creator of set theory. Then he spent 15 years in David Hilbert's circle in Goetingen. From 1878 to 1916, (from the ages of 19 to 57), Husserl was in contact with the greatest mathematicians of his time that neither Bertrand Russell nor Gottlob Frege, nor their followers, came much into contact.

Husserl also had a doctrine of sense and reference that is essentially platonic. He criticized severely psychologism in his "Prolegomena to Pure Logic" in his "Logical Investigations", and never stepped back from that position, contrary to what many husserlians believe. He formulated an epistemology of math and logic, in a platonist sense, a thing Frege nor any platonist ever made with much satisfaction.

Husserl provides his doctrine that states of affairs are the reference of assertive sentences, and the reference base is a situation of affairs. Using this philosophy, Guillermo Rosado Haddock proposes a platonist solution to the problem that has puzzled mathematicians and philosophers: the interderivability of seemingly unrelated statements in logic and mathematics. Rosado also brilliantly responds to of Benacerraf's, Quine's, Putnam's and Field's anti-platonist statements.