This is by way of being a digression; but, for a clear understanding of this main drama of the Ring, it is absolutely necessary that we should see the source of Wotan’s troubles, and here it is:  that Fricka will not allow him, figuratively, to jump off a house-top without breaking his neck.  What she tells him swiftly proves true.  Freia flies in, pursued by the Giants, who demand to be paid.  “You rule by treaties alone,” they say.  Wotan looks anxiously round for Loge, the treacherous god of fire and lies.  He has promised to find something that the Giants will accept instead of Freia; and when he enters he confesses to failure—­there is nothing, in the estimation of an earth-born creature, that is equal to a woman.  But he tells of the theft of the gold; the Giants listen greedily, and they agree to take it, if Wotan can get it, instead of Freia.  Wotan has a double motive:  he does not want all the gold, or, indeed, any of it, save the Ring shaped by the Nibelung; that he determines to grasp, else the Nibelung will become his master.  He has trusted to lies and trickery, and has been swindled; but so overpowering is his thirst for universal rule that he again trusts himself to Loge.  The Giants hold Freia as a hostage; presently all the gods begin to lapse into a comatose state—­they have not eaten of her apples that day—­and in desperation Loge and Wotan set out for the Nibelung’s abode.  The Nibelungs are the slaves and sons of toil; they labour incessantly for Alberich; him only does Wotan fear:  he must get the Ring from them at all costs.  The pair descend into the Nibelung’s cave.  The Ring is already forged, and the Tarnhelm—­the cap of invisibility—­is made which enables him to render himself invisible or to change himself into any animal he wishes.  By a trick Wotan gets Alberich into his power, carries him to the upper earth, and only lets him go free after he has surrendered Tarnhelm, Ring and all the hoard of gold.  Then the turn of the Giants comes.  The pile of gold they demand must hide Freia from sight; and in the end she can still be seen, and Wotan must sacrifice the one thing precious to him, the Ring.  That is accursed, and no sooner have Fafner and Fasolt got it than they quarrel; Fafner kills Fasolt, and goes off with all to change himself into a dragon and to hide himself in a cavern with his treasure.  Wotan, in his extremity, has summoned Erda, the wisdom of the earth, and she has counselled him to give up the Ring, and it is with horror that he sees how wise she was.  But his ambition is boundless; he cannot give up the idea of reigning supreme; and when things seem at their worst he has a sudden inspiration—­that, already mentioned, of raising up a hero who will freely take the Ring from Fafner, and, by letting Wotan have it, free of treaties, enable him to reign supreme.  The thought is told us only in the music, and in the music only in the light of the later operas of the series.  Then the gods cross a rainbow bridge, somewhat hastily thrown up by Donner, the god of storms, and enter Valhalla; and underneath the dreary wail of the Rhinemaidens is heard as they lament their loss.  With this the Rhinegold closes.