I was just reading Mark 15:17-20 (ESV) (emphasis mine):
And they clothed him in a purple cloak, and twisting together a crown of thorns, they put it on him. And they began to salute him, “Hail, King of the Jews!” And they were striking his head with a reed and spitting on him and kneeling down in homage to him. And when they had mocked him, they stripped him of the purple cloak and put his own clothes on him. And they led him out to crucify him.
Is this why purple is the color of Lent?