The theory of free relativistic fields is shown to arise in a unified manner from higher-order, configuration-space, irreducible representations of the Poincare group. A de Sitter subalgebra, in the massive case, and a Poincare subalgebra, in the massless case, of the enveloping algebra of the Poincare group are the suitable higher-order polarizations. In particular, a simple group-theoretic derivation of the Dirac equation is given.
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