"I fear such things would not be possible where I am from, not at present." Daneel is almost apologetic. "'Your kind,' as you put it, are unlikely to exist in the reality I come from. This is the case for many individuals I have met here."

He's not sure whether that's good or bad; it throws so many variables into calculating the path of humanity -- already an impossible task -- that the Zeroth Law would become even more difficult than it already is.