The space within
You cannot measure the amount of energy inside an atom. Similarly, you cannot measure the full potential of a human being. The nature of a human being is quite similar to that of an atom. The core of an atom is positive. The negatively charged particles are only on the periphery of the atom. Similarly, the negativity of a person is not their true nature; it is just on the periphery. One is said to be "centered" when he or she is calm, steady and pleasant.
How do we know whether the knowledge that we have is correct or not? Even 10,000 years ago, people knew that Jupiter had 63 moons. They used the subjective way of knowing things -- by intuition and quieting the mind. When the mind becomes calm (it is like being in a state of deep rest though one is totally alert), then an intention is taken. With that intention comes intuition, knowledge as well as inspiration. Using this method, ancient sages derived knowledge about the universe and developed mathematical techniques that are valid today. Age-old calendars can still tell exactly what time an eclipse will happen. Ancient societies in the East knew that the sun is at the center of the solar system and planets move around it. They used the method of intuitive awareness in which one feels that every cell in his body is fully alive now, and the mind is quiet. You call that Samadhi.
Read the entire article on The Washington Post.