The following was originally published December 16, 2009 at http://silvia-sijore.blogspot.com/2009/12/figura-y-fondo.html
http://www.youtube.com/watch?v=8dUiTI2AFU8&feature=player_embedded

CURIOSO VÍDEO EN EL QUE UN VASO DE RUBIN IRREGULAR DA LA SENSACIÓN DE DOS PERSONAS HABLANDO.
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