Apart from selfish reasons, such as fear of punishments, fear of blame, of dishonour, etc, there remains only two motives that can stop (or prevent, "empâecher", Fr.) men from acting badly; the natural sense of commiseration (or "sympathy", - "commisération", Fr.) for one's fellow men - compassion, and the influence of education, by association of ideas ("par l'association d'idées", Fr.) - habit.
Unfortunately, love and compassion have been omitted from too many spheres of social interaction for too long. Usually confined to family and home, their practice in public life is considered impractical, even naive. This is tragic.
Just as the grammarian makes one study grammar,
A Buddha teaches according to the tolerance of his students;
Some he urges to refrain from sins, others to do good,
Some to rely on dualism, other on non-dualism;
And to some he teaches the profound,
The terrifying, the practice of enlightenment,
Whose essence is emptiness that is compassion
And were your back as broad as heaven, and your purse full of gold, and did your compassion reach from here to hell itself, there is nothing you can do.
For fear of causing terror to living beings, Mahamati, let the Bodhisattva who is disciplining himself to attain compassion, refrain from eating flesh.
A human being is a part of the whole called by us universe; a part limited in time and space. He experiences himself, his thoughts, and his feelings as something separate from the rest - a kind of optical delusion of consciousness.
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.
The wounded surgeon plies the steel
That questions the distempered part;
Beneath the bleeding hands we feel
The sharp compassion of the healer's art
Resolving the enigma of the fever chart.