When we speak of a calm state of mind or peace of mind, we shouldn't confuse that with an insensitive state of apathy. Having a calm or peaceful state of mind doesn't mean being spaced out or completely empty. Peace of mind or a calm state of mind is rooted in affection and compassion and is sensitive and responsive to others.
If indeed the qualities such as love, patience, tolerance, and forgiveness are what happiness consists in, and if it is also true that compassion, defined as concern for others, is both the source and the fruit of these qualities, then the more we are compassionate, the more we provide for our own happiness.
I would like to explain the meaning of compassion, which is often misunderstood. Genuine compassion is based not on our own projections and expectations, but rather on the rights of the other: irrespective of whether another person is a close friend
The indifference, callousness and contempt that so many people exhibit toward animals is evil first because it results in great suffering in animals, and second because it results in an incalculably great impoverishment of the human spirit.
Modern Darwinism makes it abundantly clear that many less ruthless traits, some not always admired by robber barons and Fuhrers - altruism, general intelligence, compassion - may be the key to survival.
Ultimately, the reason why love and compassion bring the greatest happiness is simply that our nature cherishes them above all else. The need for love lies at the very foundation of human existence.