The twelfth century Cistercian reform movement was characterized by both mystical sensibility and practical wisdom. Among its lesser known figures (but one deserving to be better known) is the abbot, Isaac of Stella.
Today's "Office of Readings" offers an example of the concrete teaching he gave to his community:
This is what the law of Christ is like, the Christ who bore our griefs in his passion and carried our sorrows in his compassion for us, loving those whom he carried and carrying those whom he loved. On the other hand, whoever turns on his brother in the brother’s time of need, who exploits his weakness, whatever that weakness may be – without doubt he has subjected himself to the law of Satan and is carrying it out. Let us have compassion for each other and love the brotherhood we share, bear each other’s weaknesses and fight against each other’s vices.
Whatever religious practice or observance it leads to, any teaching or discipline that fosters a stronger love of God and, through God, of our neighbours, is most acceptable to God for that reason. This love is the reason why things should be or not be, why they should remain the same or be changed. This love should be the reason why things are and the end to which all things are directed. For nothing can be considered wrong that is truly directed towards and according to that love.
A fine presentation of the great Cistercian writers, including Isaac, can be found in volume two of Bernard McGinn's monumental, The Presence of God: A History of Western Mysticism.