Further to fathom Aquinas on this matter, however, it is useful to remember that, when he explains what goodness is, he typically says that to be good is, quite generally, the same as being desirable. (On Evil, introduction, by Brian Davies)
I think there is ambiguity in this sentence. I can understand "further" to mean "furthermore". Also "further" can be seen as tightly following "fathom". More probably, I think the author means "to fathom further...". If so, I think the word order better remains to be "to fathom further.."