Emptiness

"An understanding of ku [emptiness] helps us to see that, despite how we may see them, things--people, situations, relationships, our own lives--are not fixed, but dynamic, constantly changing and evolving. They are filled with latent potential which can become manifest at any time."
The concept of shunyata (Sanskrit), or ku (Japanese), has been variously translated as latency, non-substantiality, emptiness and void. One of the first detailed articulations of this idea comes from the Buddhist scholar Nagarjuna, living in India between 150 and 250 C.E. Nagarjuna believed that the state of "neither existence nor nonexistence" described in this concept expressed the true nature of all things. The paradoxical nature of this idea, however, makes it somewhat foreign to Western dualistic logic, and has helped contribute to a stereotype of Buddhism as a detached, mystical philosophy which sees the world as a grand illusion. The implications of ku, however, are much more down-to-earth, and are in fact consistent with the findings of contemporary science.
Modern physics, in attempting to discover the essence of matter, has arrived at a description of the world that is very close to that of Nagarjuna. What scientists have discovered is that there is no actual, easily identifiable "thing" at the basis of matter. Subatomic particles, the building blocks of the physical world that we inhabit, appear to oscillate between states of being and nonbeing. Instead of a fixed "thing" in a particular place, we find only shifting waves of probability. At this level, the world is actually a highly fluid and unpredictable place, essentially without substance. It is this non-substantial nature of reality that the concept of ku describes.
Ku also elucidates the latent potential inherent in life. Consider how, when we are in the grip of a powerful emotion, such as anger, this expresses itself in our entire being--our glaring expression, raised voice, tensed body and so on. When our temper cools, the anger disappears. What has happened to it? We know anger still exists somewhere within us, but until something causes us to feel angry again, we can find no evidence of its existence. To all intents and purposes, it has ceased to exist. Memories are another example; we are unaware of their existence until they suddenly rise into our consciousness. The rest of the time, as with our anger, they are in a state of latency, or ku: they exist and yet they do not.
An understanding of ku, therefore, helps us to see that, despite how we may see them, things--people, situations, relationships, our own lives--are not fixed, but dynamic, constantly changing and evolving. They are filled with latent potential which can become manifest at any time. Even the most seemingly hopeless situation has within it astoundingly positive possibilities.
It is very natural for us to apply various types of definitions to people, situations and ourselves, in order to make sense of the world. Unless we are careful about the nature of our thoughts and opinions, however, we can easily become trapped in narrow and often negative views: "He's not a very nice person," "I'm no good at relationships," "There will never be peace in the Middle East." As soon as we make up our minds about something in this way, we impose a limitation on it, shutting out the possibilities of positive growth and development.
When we choose to view things in term of their infinite positive potential, however, our thoughts and actions become a constructive influence, helping create the conditions for that potential to become a reality.
Because of the intimate interconnectedness of all things, each of us, at each moment, has a profound impact on the shared reality of life. The way we see things has a definite, defining effect on reality. Realizing this enables us to act with the confidence that we can shape reality toward positive outcomes.
The most positive and constructive view is to believe in the unbounded positive potential inherent in all life. Buddhism terms this potential--the true nature of life--"Buddhahood," which Nichiren defined as Nam-myoho-renge-kyo. Nichiren encouraged his followers to chant this phrase with the firm conviction that by doing so they are tapping the latent potentiality of Buddhahood in themselves and in the situations they are part of.

Source: http://www.sgi.org/buddhism/buddhist-concepts/emptiness.html