A politician divides mankind into two classes: tools and enemies. That means he knows only one class: enemies.

Friedrich Nietzsche (1844-1900) German philosopher and poet

(Attributed)
    (Source)

This is frequently attributed to Nietzsche, without citation -- a clue that it is a paraphrase of a more complex or nuanced passage. I found only one reference online that mentioned a source -- Nietzsche's Human, All Too Human (1880) -- but a search through multiple translations did not uncover this sentiment.