Humans are distinguished from other species by a massive brain that enables us to imagine a future and influence it by what we do in the present. By using experience, knowledge and insight, our ancestors recognized they could anticipate dangers and opportunities and take steps to exploit advantages and avoid hazards.
Our most fundamental social need, it turns out, to my amazement, is love. Now, I'm not a hippie-dippie whatever. If you look at the literature, our most fundamental need for children is an environment of maximum love, and that they can be hugged, kissed, and loved. That's what humanises us and allows us to realise our whole dimension.
Everybody knows someone like that: wonderful, attractive people full of passion and ideals. You envy them, but you know there's a dark side, which is brutal and cruel and violent. That dark side informs what's wonderful about them, and the passion and rage inform the darkness; they're inseparable.