The word &quot;smart&quot; appears in the title of the book being publicised, and in the title of the article, but appears <i>nowhere else</i> in the article. The comments here, and the title of the article, are quite misleading about the content of the article.<p>&quot;Smart&quot; has little or nothing to do with it. It so happens that whether you&#x27;re smart or not is <i>not</i> a predictor of your happiness. The article might as well be called &quot;Why so many people born on Tuesdays aren&#x27;t happy.&quot;