Who has the authority to give brotherly advice and what kind of authority does such advice come with? In order to answer these questions, one must reconstruct Spinoza’s understanding of authoritas which takes many forms, including prophetic, Scriptural, private, public, divine, and priestly authority. The specific authority associated with free philosophizing is, however, an “authority to teach and advise.” This authority belongs to all human beings as an inalienable natural right. It is, moreover, a private authority which is exercised in relation to others and therefore also has a public dimension. It is shown how the association of free philosophizing with such natural authority to teach and advise sets it apart from a mere legal permission to speak one’s mind. Finally, the chapter discusses Spinoza’s conception of “violent rule,” defined as any political attempt to deprive citizens of their inalienable natural right to teach and advise.