And the magician of Allathurion answered: ‘He is the dragon-crocodile who haunts the Northern marshes and ravages the homesteads by their marge. And the hide of his back is of steel, and his under parts are of iron; but along the midst of his back, over his spine, there lies a narrow strip of unearthly steel. This strip of steel is Sacnoth, and it may be neither cleft nor molten, and there is nothing in the world that may avail to break it, nor even leave a scratch upon its surface. It is of the length of a good sword, and of the breadth thereof. Shouldst thou prevail against Tharagavverug, his hide may be melted away from Sacnoth in a furnace; but there is only one thing that may sharpen Sacnoth’s edge, and this is one of Tharagavverug’s own steel eyes; and the other eye thou must fasten to Sacnoth’s hilt, and it will watch for thee. But it is a hard task to vanquish Tharagavverug, for no sword can pierce his hide; his back cannot be broken, and he can neither burn nor drown. In one way only can Tharagavverug die, and that is by starving.’ Then sorrow fell upon Leothric, but the magician spoke on: ‘If a man drive Tharagavverug away from his food with a stick for three days, he will starve on the third day at sunset. And though he is not vulnerable, yet in one spot he may take hurt, for his nose is only of lead. A sword would merely lay bare the uncleavable bronze beneath, but if his nose be smitten constantly with a stick he will always recoil from the pain, and thus may Tharagavverug, to left and right, be driven away from his food.’ Then Leothric said: ‘What is Tharagavverug’s food?’ And the magician of Allathurion said: ‘His food is men.’ But Leothric went straightway thence, and cut a great staff from a hazel tree, and slept early that evening. But the next morning, awaking from troubled dreams, he arose before the dawn, and, taking with him provisions for five days, set out through the forest northwards towards the marshes. For some hours he moved through the gloom of the forest, and when he emerged from it the sun was above the horizon shining on pools of water in the waste land. Presently he saw the claw-marks of Tharagavverug deep in the soil, and the track of his tail between them like a furrow in a field. Then Leothric followed the tracks till he heard the bronze heart of Tharagavverug before him, booming like a bell.