Paragraph 10, Zeile 10 Philosophia: De Amicitia von Cicero Cicero Paragraph 12, Zeile 52 Epistulae Morales Ad Lucilium: Epistulae Morales, Liber XI-XIII von Seneca Seneca Abschnitt LXXXVI. Seneca Lvcilio Suo Salutem, Paragraph 5, Zeile 21