After the death of Siegmund, Sieglinde takes refuge in the depths of the forest, where she gives birth to Siegfried.  In her dying moments she intrusts him to Mime, who forged the ring for Alberich when he obtained possession of the Rhinegold.  The young hero has developed into a handsome, manly stripling, who dominates the forests and holds its wild animals subject to his will.  He calls to the birds and they answer him.  He chases the deer with leaps as swift as their own.  He seizes the bear and drags him into Mime’s hut, much to the Nibelung’s alarm.  But while pursuing the wild, free life in the forest, he has dreams of greater conquests than those over nature.  Heroic deeds shape themselves in his mind, and sometimes they are illuminated with dim and mysterious visions of a deeper passion.  In his interviews with Mime he questions him about the world outside of the forest, its people and their actions.  He tires of the woods, and longs to get away from them.  Mime then shows him the fragments of his father’s sword, which had been shattered upon Wotan’s spear, the only legacy left her son by Sieglinde, and tells him that he who can weld them together again will have power to conquer all before him.  Mime had long tried to forge a sword for Siegfried, but they were all too brittle, nor had he the skill to weld together the fragments of Siegmund’s sword, Nothung.  The only one who can perform that task is the hero without fear.  One day Siegfried returns from a hunting expedition and undertakes it himself.  He files the fragments into dust and throws it into the crucible, which he places on the fire of the forge.  Then while blowing the bellows he sings a triumphant song ("Nothung!  Nothung! neidliches Schwert"), which anticipates the climax towards which all the previous scenes have led.  As he sings at his work Mime cogitates how he shall thwart his plans and get possession of the sword.  He plots to have him kill Fafner, the giant, who has changed himself into a dragon, for the more effectual custody of the Rhine-treasure and the ring.  Then when Siegfried has captured the treasure he will drug him with a poisoned broth, kill him with the sword, and seize the gold.  Siegfried pours the melted steel into a mould, thrusts it into the water to cool, and then bursts out into a new song, accompanied by anvil blows, as he forges and tempers it, the motive of which has already been heard in the “Rhinegold” prelude, when Alberich made his threat.  While Mime quietly mixes his potion, Siegfried fastens the hilt to his blade and polishes the sword.  Then breaking out in a new song, in which are heard the motives of the fire-god and the sword, he swings it through the air, and bringing it down with force splits the anvil in twain.  The music accompanying this great scene, imitating the various sounds of the forge, the flutter of the fire, the hissing of the water, the filing of the sword, and the blows upon the anvil, is realism carried to the very extreme of possibilities.