DE MONARCHIA OF DANTE ALIGHIERI
CHAPTER VI: Argument from the election and deposition of Saul by Samuel.
1. Moreover, they take from the first book of Kings the election and deposition of Saul, and declare that, according to the text, Saul, an enthroned king, was dethroned by Samuel executing God's command as His Vicar.  And they reason from this that as the Vicar of God then had authority to give temporal power, to take it away, and to transfer it to another, so now God's Vicar, High Priest of the Church Universal, has like authority to bestow, to withdraw,  and even to consign to another the sceptre of temporal dominion. From this would follow undoubtedly, as they claim, that the Empire is a derived power.
2. But to destroy the premise that Samuel was Vicar of God, we need only reply that he was not Vicar; he acted merely as a special envoy for this commission, or as a messenger bringing an express command from his Lord. This is evident from the fact that what God bade him, that alone he did and that alone recounted.
3. Wherefore let it be understood that it is one thing to be a vicar, and another to be a messenger or minister; as it is one thing to be a doctor, and another to be an interpreter.  Now a vicar is one to whom has been assigned jurisdiction according to law or to his arbitrary judgment; and so within the boundaries of the jurisdiction assigned to him he may determine legally or arbitrarily matters of which his lord has no knowledge.  But an envoy, in so far as he is an envoy, cannot do so, for as the hammer operates only through the strength of the smith, so the envoy acts only through the will of the person who delegates him.  Nor does it follow, though God did this when Samuel was His envoy, that the Vicar of God can do it. For through His angels God has achieved, is achieving, and will achieve, many things which the Vicar of God, the successor of Peter, was powerless to do.
4. Their argument is constructed from the whole to the part like this: Man can hear and see; therefore the eye can hear and see. However, it would hold negatively: Man cannot fly; therefore the arms of man cannot fly. And in the same way, according to the belief of Agathon,  God cannot through a messenger undo what has been done; therefore His Vicar is unable to do so.
1. 1 Sam. 10. 1, Samuel anoints Saul; 15. 23, he deposes him; 15. 28, he transfers the authority of ruler "to a neighbour of thine, that is better than thou."
2. Decretals of Gregory, 2. 13. 3: "The Pope has power to depose the Emperor for legitimate causes." Boniface VIII not only deposed Philip the Fair, but offered the French crown to Emperor Albert I.
3. "Sicut aliud est esse doctorem, aliud esse interpretem."
4. Witte quotes from the Decretals of Gregory IX, 1. 28. 5: "A vicar can do whatever pertains to the jurisdiction of him in whose stead he acts."
5. Gen. Anim. 5. 8. The figure is again used Par. 2. 128: "The movement and virtue of the holy circles, as from the smith the craft of the hammer, must needs from the blessed movers have their breath."
Conv. 4. 23. 2: "The fire and the hammer are efficient causes of the knife, although the principal cause is the smith."
6. Eth. 6. 2. 6: "But what is past does not admit of being undone; therefore Agathon rightly says, 'Of this alone even God is deprived, the power of making things that are past never to have been.'"
Agathon is mentioned as being one of the Greek poets in Limbo Purg. 22. 107. Historically, nothing is known of this poet except his friendship with Socrates, Plato, and Euripides, and the references to him in Aristotle's Poetics and Rhetoric.