Diadochus was an influential ascetic of the fifth century. He was born around 400 and died probably between 474 and 486. Photiké, of which he is known to have been bishop in 451, is small town in the province of Old Epira, in the north-western part of present-day Greece.

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).