The introduction of semiconductor elements has greatly stimulated interest in active, lumped, nonbilateral network theory. This paper sets out to answer the following fundamental question: Are there, by analogy to the three ideal passive elements,R, LandC, a group or set of ideal active elements, and if so, what are their properties? The search for an answer leads to the postulate of an hypothesis on electromagnetism which states: Every electromagnetic action is of a causal and irreversible physical nature. On this hypothesis is based a dual pair of ideal active elements also called the transactor elements. Their properties are discussed at length and a symbolism is introduced which extends and modifies network topology. The study of the resistive feedback connection of these elements leads to the conclusion that Ohm's law in its present form is incompatible with a consistent, harmonious theory of networks. After lengthy discussion, Ohm's law is modified and an hypothesis on dissipation is stated. Finally it is shown, that only transactor elements having real transmittance need be considered fundamental and this is summarized by an hypothesis on activity.