Thomas thinks that grateful repayment of favors should match the sentiment of the giver rather than the deed or thing give. One of the objections is we can’t know what a benefactor is thinking: “We cannot base our actions on the unknown. God alone knows the heart of man. The return of favor, then, cannot be gauged by the spirit behind them” (ST 106, 5).
To this, Thomas replies that “God alone sees the heart a it really is,” but adds “as this is manifested is certain signs (per aliqua signa manifestatur), a human being can also know it.”
There’s a profound pastoral point in that reference to signa, but we need to catch both sides of it. On the one hand, it means that other people are capable of knowing the spiritual state of a person. People are not entirely opaque to one another. Yet their motives, desires, inner purposes, loves and hates are known only through signa, and so must be interpreted. Just as people can use verbal signa to lie, so they can cover evil motives with the signa of generosity and goodness. And beyond deliberate manipulations of signs, there are the ambiguities associated with the interpretation of any sort of signa. Pastoral care is a hermeneutical discipline.
Pastors err if they think they can see past the signs to the heart; only God does that. Pastors err if they think that signs can be read without interpretation or judgment. Yet pastors err too, Thomas insists, when they throw their hands in a despair that is hard to distinguish from laziness and irresponsibility.