Field theory refers to the branch of Physics that studies how energy distributes itself within physical systems. In some systems, such as the solar system , energy can distribute itself freely. In other systems such as an electric circuit, energy must pass through wires, condensers, resistors, and so forth. However, in either type of system, energy will always distribute itself in the simplest, most symmetrical way possible under the circumstances. According to the Gestaltists, the brain is a physical system whose activity could be understood in terms of Field theory.