No one is able to rule unless he is also able to be ruled.
nemo autem regere potest nisi qui et regi.
Original text (Latin)
Notes from Wikiquote
De Ira (On Anger): Book 2, cap. 15, line 4 | From The Imitation of Christ, Liber I, cap. 20 (Of the Love of Solitude and Silence), line 2 : by Thomas à Kempis (1380-1471).