Subject info:
Flaying of Marysas - marble (original by Pio Fedi 1866) now in Loggia dei Lanzi, Florence. The unfortunate Satyr Marysas found a cursed flute and learned to play it very well, so much so he boasted he was better than Apollo. Apollo challenged him to a contest, that the Nine Muses would judge. The winner would determine the punishment of the loser. Apollo won and chose to punish Marysas by flaying him alive. This sounds like very harsh punishment, but the Greeks considered boastful arrogance a sin and referred to it as "hubris."

The Greek story:
Now Marsyas was an accomplished flute-player, for some time before he had found the flute which Athena had thrown away because it made her ugly. Some have said that Hyagnis invented the flute, but others affirm that the first long flute was made by Athena out of deer bones, or by piercing boxwood with holes wide apart, and that, proud of her invention, she came to the banquet of the gods to play. However, Aphrodite and Hera, seeing Athena's cheeks puffed out, mocked the latter in her playing and called her ugly. This is why Athena came to a spring in Mount Ida in order to view herself in the water; and having looked at herself in the water of the spring, she understood why she was mocked, and threw away the flute, vowing that whoever picked it up would be severely punished:

"The sound was pleasing; but in the water that reflected my face I saw my virgin cheeks puffed up. I value not the art so high; farewell my flute!" [Athena. Ovid, Fasti 6.697]

He who found the flute was the shepherd Marsyas, who having learned by art and practice to produce ever sweeter sounds, happened to meet Apollo and his lyre. He then challenged the god to a musical contest, which took place, some say, in the mentioned city of Nysa, being either the Nysaeans or the MUSES the judges. They also agreed that the victor should do what he wished with the defeated.

Some have told that Marsyas was departing as victor when Apollo, turning his lyre upside down, played the same tune, a prowess that Marsyas could not do with the flute. But others affirm that Marsyas was defeated when Apollo added his voice to the sound of the lyre. Marsyas protested, arguing that the skill with the instrument was to be compared, and not the voice. However, Apollo replied that when Marsyas blew into the pipes, he was doing almost the same thing as himself. And the argument presented by Apollo was judged by the Nysaeans, or by the MUSES, to be the most just, and that is why, after comparing their skills again, Marsyas was defeated. Some have said that it was on this occasion that King Midas got the ears of an ass.

Having won the contest, Apollo flayed Marsyas alive while the unfortunate musician hanged on a tall pine-tree, or else he let a slave from Scythia do this. And while his skin was stripped off the surface of his body that was but one wound, Marsyas complained:

"Why do you tear me from myself? Oh, I repent! Oh, a flute is not worth such a price!" [Marsyas. Ovid, Metamorphoses 6.385]

More information on other sculpture.