Leo was born in Etruria and became Pope in 440. He was a true shepherd and father of souls. He constantly strove to keep the faith whole and strenuously defended the unity of the Church. He repelled the invasions of the barbarians or alleviated their effects, famously persuading Attila the Hun not to march on Rome in 452, and preventing the invading Vandals from massacring the population in 455.

The theological virtue of hope is symbolized by the colour green, just as the burning fire of love is symbolized by red. Green is the colour of growing things, and hope, like them, is always new and always fresh. Liturgically, green is the colour of Ordinary Time, the orderly sequence of weeks through the year, a season in which we are being neither single-mindedly penitent (in purple) nor overwhelmingly joyful (in white).