New Yorkers are trying to determine if the seven subway slashings that made headlines in January are connected or not connected. Police Commissioner Bill Bratton thinks they are not. This is the kind of thing that just happens now and then. It comes and it goes like the wind in a forest.

But it's hard not to see a pattern in all of this. Indeed, a slashing occurred on the very last day of January, which was also the safest month on record for the system. What could be going on? Maybe it is this: Deaths in the underground are alarming because they rarely happen.

In 2014, for example, an average of 5.6 million people rode the subway during the weekday and 6 million during the weekend. From these figures, we can guess that around 160 million people used the subway in January 2016. Out of that huge number, only seven got stabbed in the face or hand.

Also, in 2013, there were a total of 53 deaths in the subway and about 1.70 billion riders. What these numbers show is that the subway system is an amazingly safe place. But getting slashed in the face by a complete stranger will grab the headlines every time.

And it is the stranger who is the important factor in these crimes. There is a fascination with violence that is peculiar to New Yorkers. For them, injuries or deaths caused by strangers grip the imagination fast. NYC is, after all, the American capital of the radically unknown person. Seattle does not know of these kinds of strangers. Our killers are somewhat familiar.