Beauty is a state of wholeness.
We live in a single, perfect system of nature, and beauty is the completion of all positive and negative qualities existing harmonious together in nature.
We perceive this beauty, this wholeness, when we sense the complementarity of positive and negative qualities, thus acknowledging the interdependence and realizing the harmonious coexistence of all parts of nature—still, vegetative, animate and human.
Reaching this state of wholeness requires developing a loving attitude to others. Mothers naturally see their babies as beautiful because they love them. A loved one is always beautiful.
Developing love beyond the inborn natural realm of families to society at large, i.e., to people we naturally do not hold any special care for, requires developing the ability to feel the desires of others in order to fulfill them. The more we feel desires in others with the aim of fulfilling those desires, the more we develop care, which grows into love, and we then perceive those whom we love as beautiful. There is a phenomenon of parents loving their adopted children no less and sometimes even more than their biological children. They try to give and fulfill the adopted children more in order to become worthy of their love, and they can then end up loving them even more.
Beauty thus appears when love is present. When love and connection appear upon inner detachment and resistance, a state called “love will cover all crimes” in the wisdom of Kabbalah, then those we come to love end up becoming as beautiful as babies are to their own mothers.