Tabini was at least canny enough in the differences between atevi and human to know that, gut level, he might think he understood - but chances were very good that he wouldn't, couldn't, and never would, unaided by the paidhi, come up with the right forecast of human behavior because he didn't come with the right hardwiring. Average people didn't analyze what they thought: they thought they thought, and half of it was gut reaction.
