Why did Dr. Livesey say that the tattoo near the captain’s shoulder seemed prophetic? (find the meaning of the word, prophetic first)

"A fair wind," and "Billy Bones his fancy," were very neatly and clearly executed on the forearm; and up near the shoulder there was a sketch of a gallows and a man hanging from it--done, as I thought, with great spirit.

"Prophetic," said the doctor, touching this picture with his finger. "And now, Master Billy Bones, if that be your name, we'll have a look at the colour of your blood. Jim," he said, "are you afraid of blood?"

From the text, we can infer that Dr. Livesey recognized the Captain as a criminal, meaning the prophecy (the gallows) might be his end.