In his book “True Love: A Practice for Awakening the Heart,” the Vietnamese monk Thích Nhất Hạnh elaborated on the brahmavihārās, a series of four virtues and corresponding meditation practices made to cultivate them. Of the first — maitri, or loving-kindness — Thích Nhất Hạnh wrote that, because “understanding is the essence of love,” one must practice being attentive, looking deeply, and understanding one’s beloved. The second virtue is karuna, or compassion, which involves not just the desire to ease another’s pain, but the ability to do so. Third, mudita roughly translates to empathetic joy: “If there is not joy in love,” Thích Nhất Hạnh wrote, “it is not true love.” Of the fourth, upeksha, or equanimity, he observed, “In true love, you attain freedom. When you love, you bring freedom.”