"Such men were dangerous"

Public Domain"Julius Caesar" from the First Folio
This is a reference to a line spoken by the title character of William Shakespeare’s “Julius Caesar.” Early in the play, in Act I, scene ii, Caesar notices Cassius, one of the leaders of the conspiracy that will assassinate him shortly, and remarks to Mark Antony, “Yond Cassius has a lean and hungry look: / He thinks too much; such men are dangerous.”

Lieutenant Scheisskopf has a similar reaction to Clevinger because he “had a mind, and … people with minds tended to get pretty smart at times.”