The scope of the unwritten books is, however, of little importance in comparison with the execution of the existing portion of the poem. The Argonaut Saga has its weaknesses as a theme for epic. It is too episodic, it lacks unity and proportion. Save for the struggle in Colchis and the loves of Jason and Medea, there is little deep human interest. These defects, however, find their compensation in the variety and brilliance of colour, and, in a word, the romance that is inseparable from the story. The scene is ever changing, each day brings a new marvel, a new terror. Picturesqueness atones for lack of epic grandeur. For that reason the theme was well suited to the Silver Age, when picturesqueness and rich invention of detail predominated at the expense of poetic dignity and kindling imagination. In many ways Valerius does justice to his subject, in spite of the initial difficulty with which he was confronted. Apollonius Rhodius had made the story his own; Varro of Atax had translated Apollonius: both in its Greek and Latin forms the story was familiar to Roman readers. It was hard to be original. Much as Valerius owes to his greater predecessor, he yet succeeds in showing no little originality in his portrayal of character and incident, and in a few cases in his treatment of plot.[489] In one particular indeed he has markedly improved on his model; he has made Jason, the hero of his epic, a real hero; conventional he may be, but he still is a leader of men. In Apollonius, on the other hand, he plays a curiously inconspicuous part; he is, in fact, the weakest feature of the poem; he is in despair from the outset, and at no point shows genuine heroic qualities; he is at best a peerless wooer and no more. Here, however, he is exalted by the two great battles of Cyzicus and Colchis; it is in part his prowess in the latter battle that wins Medea's heart. In this connexion we may also notice a marked divergence from Apollonius as regards the plot. Aeetes has promised Jason the fleece if he will aid him against his brother Perses, who is in revolt against him with a host of Scythians at his back. Jason aids him, does prodigies of valour, and wins a glorious victory. Aeetes refuses the reward. This act of treachery justifies Jason in having recourse to Medea's magic arts and in employing her to avenge him on her father. In Apollonius we find a very different story. The sons of Phrixus, who, to escape the wrath of Aeetes, have thrown in their lot with the Argonauts, urge Jason to approach Medea; they themselves work upon the feelings of their mother, Chalciope, till she seeks her sister Medea--already in love with Jason and only too ready to be persuaded--and induces her to save her nephews, whose fate is bound up with that of the strangers. This incident is wholly absent from Valerius Flaccus, with the result that the loves of Jason and Medea assume a somewhat different character. Jason's conduct becomes more natural and dignified.