Ferdowsi, answered from the texts and cited to the page.
The book does both, and a man who takes only one half has not read it. Ask first what the throne is. Kai Khusrow, at the summit of his power, with every foe slain and Hind, Chin and Rum prosperous, fears that he may grow an ingrate to God, an Ahriman in faith like Zahhak or Jamshid, and that the Grace will quit him.1 The glory is held by justice and lost by pride, and the king himself knows it.
No man is exalted by the poem merely for sitting on the throne. Yet the poem will not make a rebel of the hero. The old sage tells Esfandiyār, who is torn between his father's order and his own honour, that a father's wrath is more tender than a son's best love, and that he must go, "for, whatsoe'er he doth, he is the Shah." Esfandiyār goes, and is thrown into chains by a father who cannot bear to share one crown.2
Rostam gives the other half. When the Iranians told him he was worthy of the throne while Kāvus lay bound, he cursed the speaker and said he would sooner see kingship and crown perish than sit on the golden throne with the Shah in fetters; he picked twelve thousand horsemen and freed Kāvus, Giv, Gudarz and Tus.3 Kāvus, mark, had sought to search the mysteries of God and tread the dome of heaven, and fell a wretch through his perverseness.3
The hero serves the man he has just seen disgrace himself, and he does not take what is not his. Now the hard scene, the one the poem keeps closest to its heart. Esfandiyār's messenger tells Rostam that Gushtāsp's soul is vexed that the paladin has never come to court nor paid the customary service, and that Gushtāsp says Rostam tarries at Zābul, bemused with drink.4
Rostam's answer is that he will not go to the Shah in chains. The poem honours him for the refusal and mourns what it costs him. The poem teaches that kingship is God's own appointment: "He created throne and crown and signet." Whoever stretches out his hand for it unworthily, as Fardyin did, bathes his hands in blood and is miserably slain.5
The hero may refuse the chain, he may free the king from his own folly, and he may rebuke him, but he does not take the throne for himself. Rostam is never king.
Kingship is God's institution and the world cannot stand without it: the king who keeps justice and wisdom holds the farr, the divine glory, and the land flourishes. The glory leaves the king who grows proud, as it left Jamshid, or unjust, as it never came to Żaḥḥāk. The hero serves the throne, not the man's every folly: Rostam crowns kings, saves them, rebukes them and will not be put in chains by one, and the poem honours him for it. A king is great by justice and generosity, not by birth alone; be a Fereydun therein.67
Yet let me not grow arrogant of soul, Corrupt in thought, an Ahriman in faith, And be an evil-doer like Zahhak, JamshidThe Shahnama, Vol. IV
Thou must set forward, that is mine advice, For, whatsoe'er he doth, he is the Shah.The Shahnama, Vol. V
'Shall I be on the throne of gold, the Shah Bound? Perish kingship rather! Perish crown!'The Shahnama, Vol. VIII
Gushtasp said: 'Rustam, Because of much goods, province, and stored treasure, Hath tarried at Zabul and grown bemused With drink, and none hath profit from a drunkard.'The Shahnama, Vol. V
Fear Him, the Lord, the Maker of the world, For He created throne and crown and signet.The Shahnama, Vol. IX
By holy God, by throne And crown if I shall come upon thee hostless, And if I blow a chilling blast upon thee...! Thou hast not seen me yet in fight and I Have heard but thy harsh words. I lean on Him That giveth victory.The Shahnama, Vol. VIII
One day contemplating the throne of power He deemed that he was peerless. He knew God, But acted frowardly and turned aside In his ingratitude. He summoned all The chiefs, and what a wealth of words he used! " The world is mine, I found its properties, The royal throne hath seen no king like me, For I have decked the world with excellence And fashioned earth according to my will.The Shahnama, Vol. I
The poem has been read for a thousand years as a mirror for princes and, more recently, as a record of the cost of serving bad kings; both readings find their evidence in it.