At a certain stage of maturity in the development of different fusion concepts, a unity is perceived which is lacking in the earlier, more primitive stages. Such a realization seems to have occurred to theorists investigating the stability of field-reversed particle rings, compact tori, EBT and tandem mirrors. The unifying feature in these systems is the presence of a very energetic particle component in the plasma. In the case of EBT, it is the 0.5–1.0 MeV electrons forming the stabilizing ring, for tandem mirrors it is the hot electrons in the thermal barriers, for electron rings it is the ∼ MeV electrons that provide the ring current, and for the proposed compact-torus hybrids it is the energetic large-gyroradius ions.