Michael Dewar[cite]10.1016/S0040-4039(01)82765-9[/cite] famously implicated a so-called π-complex in the benzidine rearrangement, back in the days when quantum mechanical calculations could not yet provide a quantitatively accurate reality check. Because this π-complex actually remains a relatively unusual species to encounter in day-to-day chemistry, I thought I would try to show in a simple way how it forms.