[randomswede]

One of the reasons that Contact (and Special Circumstances) have (some) humans[] around is for intuitive leaps. I can't say I recall which Culture book this is mentioned in, but it is, in one of them.

[] let's go with "human" as a general term for Culture biological citizens, it is probably a bit incorrect, but gets the point across.

[thom]

The 'referers' are in Consider Phlebas, a small group of humans among trillions who are able to reliably predict the future better than Minds. This would be one argument in Gurgeh's favour, but Banks later admitted how flimsy the idea was.