Closures are one of the most powerful features of ECMAScript (javascript) but they cannot be property exploited without understanding them. They are, however, relatively easy to create, even accidentally, ...
The field of intelligence has had its Jekyll and Hyde sides for me personally, which is why I entered the field in the first place. I became interested in intelligence when, as an elementary-school student, I did poorly on IQ tests. In fact, I did so poorly that in sixth grade I was sent back to a fifth-grade classroom to retake the fifth-grade intelligence test. In a sense, my professional career has been an attempt to understand and come to terms with my own early failures on these tests!