Treasure Island

Read the following extract carefully, then answer the question below:

At first I had supposed 'the dead man’s chest' to be that identical big box of his upstairs in the front room, and the thought had been mingled in my nightmares with that of the one-legged seafaring man. But by this time we had all long ceased to pay any particular notice to the song; it was new, that night, to nobody but Dr. Livesey, and on him I observed it did not produce an agreeable effect, for he looked up for a moment quite angrily before he went on with his talk to old Taylor, the gardener, on a new cure for the rheumatics. In the meantime, the captain gradually brightened up at his own music, and at last flapped his hand upon the table before him in a way we all knew to mean silence. The voices stopped at once, all but Dr. Livesey’s; he went on as before speaking clear and kind and drawing briskly at his pipe between every word or two. The captain glared at him for a while, flapped his hand again, glared still harder, and at last broke out with a villainous, low oath, “Silence, there, between decks!”

“Were you addressing me, sir?” says the doctor; and when the ruffian had told him, with another oath, that this was so, “I have only one thing to say to you, sir,” replies the doctor, “that if you keep on drinking rum, the world will soon be quit of a very dirty scoundrel!”

The old fellow’s fury was awful. He sprang to his feet, drew and opened a sailor’s clasp-knife, and balancing it open on the palm of his hand, threatened to pin the doctor to the wall.

The doctor never so much as moved. He spoke to him as before, over his shoulder and in the same tone of voice, rather high, so that all the room might hear, but perfectly calm and steady: “If you do not put that knife this instant in your pocket, I promise, upon my honour, you shall hang at the next assizes.”

How does the author portray Dr. Livesey's character in this scene, and what key traits are highlighted through his interactions with the captain? Use specific evidence from the text to support your answer.