The irony was delicious. The lead paragraph of the Toronto Star story on this week’s terror arrests in Canada was: “In investigators’ offices, an intricate graph plotting the links between the 17 men and teens charged with being members of a homegrown terrorist cell covers at least one wall. And still, says a source, it is difficult to find a common denominator.” But illustrating the story was a photo of two women in full Islamic dress, their faces entirely covered except for a slit for their eyes. Difficult to find a common denominator? The investigators could have found it in...