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.."
Furthermore, to fathom Aquinas on this matter, it is useful to remember..
. It looks like an editing error to me where bothfurther[more]
andhowever
remained where one should have been chosen,indef
] to remember [that ... Aquinas₁ typically says [that ... desirable]] is useful in order [forindef
] to fathom Aquinas₁ further [than some previous standard], except that some rules (like extraposition, adverb fronting, indefinite subject deletion, pronominalization, and in order deletion) have applied. Probably ill-advisedly.