All that is known for certain about Isaac is that he abandoned his studies at the cathedral schools in about 1140 and became a Cistercian monk, at the time of St Bernard’s reforms. He became abbot of the small monastery at Stella, outside Poitiers, in 1147, from where he was exiled to a remote monastery on the Ile de Ré on the Atlantic coast of Gascony, perhaps in 1167, perhaps because of his support for Archbishop Thomas Becket. Scholars incline to the view that he returned to Stella some time later and died there in about 1178. The date of his birth has been given as anywhere between 1105 and 1120.

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).