My recent "involuntary memory." Caravaggio's "The Calling of Saint-Matthew." Description of the paining from the blog: Zeitgeist sic itur ad astra ("thus to the stars"). Click here to read: (http://duluxdreams.wordpress.com/2012/06/28/caravaggio-the-calling-of-st-matthew/)
Caravaggio's Crazy Life: The Paintings of a Killer
Note the critical thought represented by the wrinkled forehead, the outstretched arm, that subtle halo.
The Incredulity of Saint Thomas - Detail - Caravaggio 1601-02, via Caravaggista blog