This thesis studies an analytic variant of a well-known separation principle from which follows Hahn-Banach theorem and many basic theorems in convex analysis. By using this analytic variant, we provide natural and elegant proofs for Agnew-Morse Theorem, the amenability of abelian groups, and the existence of Haar integrals. It is conceivable that the approach we suggest here might lead to clarification of some results in convex analysis.