The Angelic Doctor on the Errors of the Greeks - Chapter 2

How the Son is to be understood as second from the Father and the Holy Spirit third.

In the abovementioned authorities passages are found where the Son is said to be second in order from the Father and the Holy Spirit third in order from the same. For in the discourse to Serapion Athanasius says: “The Holy Spirit is third in order from the Father, but the Son is second.”  Similarly, Basil says: “In dignity and order the Spirit is second from the Son.” 

These statements may strike a person as false. For, as Augustine says, the only order existing among the divine persons is an order, not of priority whereby one comes before another, but of origin, whereby one is from another.  For there is no mode of priority in virtue of which the Father could be said to be prior to the Son. For the Father is not prior in time, since the Son is eternal; nor prior in nature, since the one nature belongs to Father and Son; nor prior in dignity, since Father and Son are equal; nor even prior in understanding, since they are distinguished only by relations, and relative entities are understood simultaneously,  since each pertains to the understanding of the other. And so it is clear that properly speaking the Son cannot be said to be second in order from the Father and the Holy Spirit third in order from the Father.

The aforementioned Doctors, therefore, call the Son second and the Holy Spirit third according to their numerical order. This is clear from Basil himself who says: “We have received the Holy Spirit from Father and Son as third numbered and conglorified, the Spirit of the very Son of God, who when instituting the order of salvific baptism said: ‘Going, baptize all men in the name of the Father and of the Son and of the Holy Spirit’.”  And Epiphanius says: “The Spirit of God who is from Father and Son is third named.” 

But when Basil asserts that the Spirit is second from the Son in dignity, he appears more seriously mistaken, because he seems to posit degrees of dignity in the Trinity, whereas all three persons are equal in dignity. This statement, however, can be explained as referring, not to natural, but to personal dignity in God, just as we say that “a person is a hypostasis in virtue of a distinct property entailing dignity.”  Hilary adopts this manner of speaking when he says  that the Father is greater than the Son by reason of authority of origin. But by reason of oneness in substance the Son is not thereby less than the Father.