When you look at the world and only see a material reality that is encased in time and space – then you have a lop-sided perception. You are seeing only the manifest aspect of creation. In this situation you are a tiny speck in an infinite universe made of matter.
When you look at the world and see the manifest world and know yourself as pure consciousness then you have a duality – Purusha and Prakriti – the silent seer and the dynamic seen. You are now free and independent of the actions of the world, though remaining in the midst of them.
When you look at the world and see only consciousness – no differentiation between seer and seen – then you have realised the Brahman: the one without second.
You may wonder what the benefit is of realising the One. It is the end of fear, because fear is born of duality. This is the summum bonum – the highest good and the fulfillment of the purpose of life.