In Libri 1, Quaestio XX, sec. 26, of Duns Scotus's In Octo Libros Physicorum Aristotelis, Duns Scotus gives expression to a common tenet of a doctrine of the Forms when he writes
[S]ed forma non cognoscitur nisi ex operationibus....
which roughly translates as "[B]ut form is not known [to us] except from [its] operations".
I have two questions about this:
Is "operationibus" dative or ablative in this construction? I know that "ex" typically takes the ablative, but Allen and Greenough's New Latin Grammar notes that "ex" + dative can occur as the Dative of Separation, a form of the Dative of Reference (sec. 381):
Note. -- The Dative of Separation is a variety of the Dative of Reference. It represents the action as done to the person or thing, and is thus more vivid than the Ablative.
That would sort of make sense if the idea was to emphasize how the Forms "impress themselves upon us". I suppose that would make the better translation something like "[B]ut form is not known [to us] except by reference to [its] operations [on us] (?)"
What is the best way to translate "operationibus"? I went with "operation", but I suspect it has a technical use or a use idiosyncratic to Medieval Latin here. Especially given that these are commentaries on Aristotle, I am tempted to think it is being used in relation to his Four Causes. Given that one translation of "operatio" given by Wiktionary is "effect, result" I'm tempted to see this as referring to the efficient causes of our knowledge of From.
EDIT: Thanks to cnread's helpful comment, question 1 is largely moot. There is no "ex"+dative, so "operationibus" is certainly ablative.