There is a basic human aspiration for the good life: Freedom (as inner peace), The Spiritual (a realm of good purpose and contentment) and becoming ONE. One can become ONE, God (by overcoming adviya).
First, let's take a look at Aurobindo's general idea of planes of existence.
Nature evolves by contradiction (see dialectics). The apparent chaos of reality brings Aurobindo's idea of Harmony (sort of the kensho of Zen Buddhism)
Harmony means a deliberate decision not to fall for adviya in a given situation. Let's take world hunger, for example. The problem of food shortage in the world is not so much due to lack of food, but lack of policies and agreements in the production and distribution of food, as well as means to develop the Third World. A higher harmony takes all the parties to move beyond ego and self-concern to solve "the problem" (Is it Capitalism?). The question makes sense, but how to approach it from the position of the individual?
The greater the disparateness, the greater the opportunity for change.Aurobindo analyzes the limits of science: 1- science is fixed in the material view of reality, 2- science does not perceive the subtle forces of life based on the vital, mental, and spiritual dimension of life, thus 3- science sees only part of the truth, not the whole of the phenomenon ("the spiritual").
Aurobindo thinks that science becomes irrational by denying other planes of life. Not so, it's not the province of science to establish something beyond its province. On the other hand, Aurobindo is right that we tend to see too linearly, preventing ourselves the acquisition of more integral forms of knowledge (what I'd call broadening our symbolic insights).
For Aurobindo, both materialism and Hindu asceticism miss the point. One negates the spiritual, the other the material. Here Aurobindo comes up with the idea of Cosmic Consciousness.
Perceiving the ONENESS: For Aurobindo, matter is a form of spirit, the body of spirit. So, matter is spirit. (There is a similarity between Aurobindo and Hegel here, though there are important differences as well).
Perceiving ONENESS means seeing differently. Also "willing" a different outlook at things. Not falling for the tamas of thought. It means embracing ALL. ACCEPT ALL. It doesn't mean falling for anomie. By understanding FACTicity (the existentialists gave up and called it absurd). One learns UNDERSTAND and respect FACTicity.
This needs to be explained in more detailed with Aurobindo's Metaphysics.