My focus today is the Holy Spirit and the Eucharist. How does the Holy Spirit figure in the Eucharistic theology of St. Thomas?

The topic, the Holy Spirit in the teaching on Eucharist, may not appear on first mention to be particularly promising.

There's no question, after all, devoted to the Holy Spirit

in the Treatise on the Eucharist in the Summa, nor, for that matter, is there such a question

included in the treaties on the sacraments in general, with which the consideration of the third

part of the Summa of the Sacraments of the New Law

opens.

And in terms of the Treaties on the Eucharist in the Summa, while there are to be sure a number

of mentions by name of the Holy Spirit, one can go several pages at a time without

such naming, without explicit acknowledgement of the Spirit,

or explicit recognition of what the Spirit does.

Is the Spirit then really that important

for an account of the Eucharist as belief and practice?

There is nonetheless much that recommends the undertaking of a presentation of the Holy Spirit

and Eucharist.

For one thing, if the Christology of Aquinas is Trinitarian, with a prominent role enjoyed

by the spirit, and this, in in fact has been shown, then the same

will hold for the account of the sacraments through which Christ's saving benefits are conveyed

to his people. In this sacrament, it is the same Christ perfected in his humanity by the grace,

virtues, and gifts infused by the spirit, and the illusion here is to Question 7 of the Tensupars, who is present and to be encountered.

So, too, Aquinas' understanding of grace suggests the Holy Spirit.

The sacraments convey grace as instrumental causes.

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