The importance of analysis in mathematics cannot be overestimated. Many areas of modern mathematics may be seen as parts of analysis while, at the same time, many areas of mathematics heavily rely on analysis to built on and further comment on their problems. Indeed many mathematicians, who consider themselves to be analysts, work on differential equations and prove numerous and powerful results regarding their behavior (enumerating these results, one could begin by mentioning the existence theorem of solutions in the O.D.E's case, and various results concerning solutions of boundary value problems in the P.D.E.'s case).