A personally guaranteed note looks, superficially, like the same sort of contract; but it isn’t. It – specifically the personal guarantee – isn’t a property interest in a thing. It attempts to assert a property interest in no thing: nothing. The fact that you cannot foreclose and collect your property demonstrates Aquinas’ point: the thing in which the contract asserts an ownership interest or other claim is no thing at all: nothing.
The apples have been eaten, the wine has been drunk, and the borrower has to take action to acquire new, different apples or wine precisely because the thing to which the mutuum lender lays claim does not exist
A mutuum for interest looks superficially like a census contract against a farmer’s field, as described by John de Lugo and affirmed as morally licit by Pius V.