milk of human kindness

Fig. natural kindness and sympathy shown to others. (From Shakespeare's play Macbeth, I. v.) Mary is completely hard and selfish—she doesn't have the milk of human kindness in her. Roger is too full of the milk of human kindness and people take advantage of him.

Compassion or benevolence. Shakespeare again, but this time Macbeth. Lady Macbeth regrets that her husband doesn't have the overwhelming ambition that she has by saying, “Yet do I fear thy nature, It is too full o' th' milk of human kindness. To catch the nearest way.” Macbeth heeds his wife, schemes and murders his way to the throne, and is then deposed and killed. The milk must have curdled. A compliment to a sweetheart of a person is to say that he or she is “full of the milk of human kindness.”