What is a charitable heart? It is a heart which is burning with love for the whole creation, for men, for the birds, for the beasts … for all creatures. He who has such a heart cannot see or call to mind a creature without his eyes being filled with tears by reason of the immense compassion which seizes his heart; a heart which is softened and can no longer bear to see or learn from others of any suffering, even the smallest pain being inflicted upon a creature. That is why such a man never ceases to pray for the animals … [He is] … moved by the infinite pity which reigns in the hearts of those who are becoming united with God.
— ISAAC OF NINEVEH