I keep myself as free as possible from conjectures and avoid therefore the effort to overturn them. This does not seem like a fruitful business to me. For conjectures are not overturned by producing more of the same. They sink away when one sees that observation is more fruitful than conjecture ... I call Wissenschaft [scholarship] the observation of what exists, not the attempt to imagine what is not visible. Perhaps one will object that the guesswork of conjecture excites and entertains while obervation is hard and difficult work. But the Gospel is misunderstood when one makes a plaything out of it.
You can find the quote in the intro to John Piper's What Jesus demands from the world.
Anyway. Schlatter, Adolph von. He da man. For sure I will be checking out his commentary on Romans when I drop in to Moore College library next Wednesday.