This is for the benefit of Winman and some others of his persuasion. I have greatly enjoyed Philip W.Comfort's work:New Testament Text And Translation Commentary. It has been very helpful. James White first wrote of this book on his blog a while ago and I'm hooked. The term NU means the NA/UBS texts and WH (well you all know what that refers to). He gives his own translations of both. He supplies a lot of additional data. I'm merely giving the gist of his treatment. WH NU : Delving into things which he has seen. Variant/TR : Delving into things which he has not seen. The WH NU reading has exceedingly superior documentary support and suits the context exactly, for Paul was arguing against the proto-gnostics who based their religion on visions they had seen. These visions of the supernatural -- even of angels -- puffed up their spiritual pride.Most likely, it was changed to "things which they had not seen" to make these spiritualists look ridiculous. "They delved into things they couldn't even see!" Though the sarcasm is effective for the reader, it misses Paul's point, which is sarcastic but more subtle: "They who claim to be spiritual, base their claims on what they say they have seen -- not on what cannot be seen, the true spiritual realities!"